summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_fb_helper.c
blob: 3d13ca6e257f0f2c6bd366a49f8b7f3622e592dd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
/*
 * Copyright (c) 2006-2009 Red Hat Inc.
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
 *
 * DRM framebuffer helper functions
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 *
 * Authors:
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sysrq.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/module.h>
#include <drm/drmP.h>
#include <drm/drm_crtc.h>
#include <drm/drm_fb_helper.h>
#include <drm/drm_crtc_helper.h>

MODULE_AUTHOR("David Airlie, Jesse Barnes");
MODULE_DESCRIPTION("DRM KMS helper");
MODULE_LICENSE("GPL and additional rights");

static LIST_HEAD(kernel_fb_helper_list);

/**
 * DOC: fbdev helpers
 *
 * The fb helper functions are useful to provide an fbdev on top of a drm kernel
 * mode setting driver. They can be used mostly independantely from the crtc
 * helper functions used by many drivers to implement the kernel mode setting
 * interfaces.
 *
 * Initialization is done as a three-step process with drm_fb_helper_init(),
 * drm_fb_helper_single_add_all_connectors() and drm_fb_helper_initial_config().
 * Drivers with fancier requirements than the default beheviour can override the
 * second step with their own code.  Teardown is done with drm_fb_helper_fini().
 *
 * At runtime drivers should restore the fbdev console by calling
 * drm_fb_helper_restore_fbdev_mode() from their ->lastclose callback. They
 * should also notify the fb helper code from updates to the output
 * configuration by calling drm_fb_helper_hotplug_event(). For easier
 * integration with the output polling code in drm_crtc_helper.c the modeset
 * code proves a ->output_poll_changed callback.
 *
 * All other functions exported by the fb helper library can be used to
 * implement the fbdev driver interface by the driver.
 */

/**
 * drm_fb_helper_single_add_all_connectors() - add all connectors to fbdev
 * 					       emulation helper
 * @fb_helper: fbdev initialized with drm_fb_helper_init
 *
 * This functions adds all the available connectors for use with the given
 * fb_helper. This is a separate step to allow drivers to freely assign
 * connectors to the fbdev, e.g. if some are reserved for special purposes or
 * not adequate to be used for the fbcon.
 *
 * Since this is part of the initial setup before the fbdev is published, no
 * locking is required.
 */
int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
{
	struct drm_device *dev = fb_helper->dev;
	struct drm_connector *connector;
	int i;

	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
		struct drm_fb_helper_connector *fb_helper_connector;

		fb_helper_connector = kzalloc(sizeof(struct drm_fb_helper_connector), GFP_KERNEL);
		if (!fb_helper_connector)
			goto fail;

		fb_helper_connector->connector = connector;
		fb_helper->connector_info[fb_helper->connector_count++] = fb_helper_connector;
	}
	return 0;
fail:
	for (i = 0; i < fb_helper->connector_count; i++) {
		kfree(fb_helper->connector_info[i]);
		fb_helper->connector_info[i] = NULL;
	}
	fb_helper->connector_count = 0;
	return -ENOMEM;
}
EXPORT_SYMBOL(drm_fb_helper_single_add_all_connectors);

static int drm_fb_helper_parse_command_line(struct drm_fb_helper *fb_helper)
{
	struct drm_fb_helper_connector *fb_helper_conn;
	int i;

	for (i = 0; i < fb_helper->connector_count; i++) {
		struct drm_cmdline_mode *mode;
		struct drm_connector *connector;
		char *option = NULL;

		fb_helper_conn = fb_helper->connector_info[i];
		connector = fb_helper_conn->connector;
		mode = &fb_helper_conn->cmdline_mode;

		/* do something on return - turn off connector maybe */
		if (fb_get_options(drm_get_connector_name(connector), &option))
			continue;

		if (drm_mode_parse_command_line_for_connector(option,
							      connector,
							      mode)) {
			if (mode->force) {
				const char *s;
				switch (mode->force) {
				case DRM_FORCE_OFF:
					s = "OFF";
					break;
				case DRM_FORCE_ON_DIGITAL:
					s = "ON - dig";
					break;
				default:
				case DRM_FORCE_ON:
					s = "ON";
					break;
				}

				DRM_INFO("forcing %s connector %s\n",
					 drm_get_connector_name(connector), s);
				connector->force = mode->force;
			}

			DRM_DEBUG_KMS("cmdline mode for connector %s %dx%d@%dHz%s%s%s\n",
				      drm_get_connector_name(connector),
				      mode->xres, mode->yres,
				      mode->refresh_specified ? mode->refresh : 60,
				      mode->rb ? " reduced blanking" : "",
				      mode->margins ? " with margins" : "",
				      mode->interlace ?  " interlaced" : "");
		}

	}
	return 0;
}

static void drm_fb_helper_save_lut_atomic(struct drm_crtc *crtc, struct drm_fb_helper *helper)
{
	uint16_t *r_base, *g_base, *b_base;
	int i;

	if (helper->funcs->gamma_get == NULL)
		return;

	r_base = crtc->gamma_store;
	g_base = r_base + crtc->gamma_size;
	b_base = g_base + crtc->gamma_size;

	for (i = 0; i < crtc->gamma_size; i++)
		helper->funcs->gamma_get(crtc, &r_base[i], &g_base[i], &b_base[i], i);
}

static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
{
	uint16_t *r_base, *g_base, *b_base;

	if (crtc->funcs->gamma_set == NULL)
		return;

	r_base = crtc->gamma_store;
	g_base = r_base + crtc->gamma_size;
	b_base = g_base + crtc->gamma_size;

	crtc->funcs->gamma_set(crtc, r_base, g_base, b_base, 0, crtc->gamma_size);
}

/**
 * drm_fb_helper_debug_enter - implementation for ->fb_debug_enter
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_debug_enter(struct fb_info *info)
{
	struct drm_fb_helper *helper = info->par;
	struct drm_crtc_helper_funcs *funcs;
	int i;

	if (list_empty(&kernel_fb_helper_list))
		return false;

	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
		for (i = 0; i < helper->crtc_count; i++) {
			struct drm_mode_set *mode_set =
				&helper->crtc_info[i].mode_set;

			if (!mode_set->crtc->enabled)
				continue;

			funcs =	mode_set->crtc->helper_private;
			drm_fb_helper_save_lut_atomic(mode_set->crtc, helper);
			funcs->mode_set_base_atomic(mode_set->crtc,
						    mode_set->fb,
						    mode_set->x,
						    mode_set->y,
						    ENTER_ATOMIC_MODE_SET);
		}
	}

	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_debug_enter);

/* Find the real fb for a given fb helper CRTC */
static struct drm_framebuffer *drm_mode_config_fb(struct drm_crtc *crtc)
{
	struct drm_device *dev = crtc->dev;
	struct drm_crtc *c;

	list_for_each_entry(c, &dev->mode_config.crtc_list, head) {
		if (crtc->base.id == c->base.id)
			return c->fb;
	}

	return NULL;
}

/**
 * drm_fb_helper_debug_leave - implementation for ->fb_debug_leave
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_debug_leave(struct fb_info *info)
{
	struct drm_fb_helper *helper = info->par;
	struct drm_crtc *crtc;
	struct drm_crtc_helper_funcs *funcs;
	struct drm_framebuffer *fb;
	int i;

	for (i = 0; i < helper->crtc_count; i++) {
		struct drm_mode_set *mode_set = &helper->crtc_info[i].mode_set;
		crtc = mode_set->crtc;
		funcs = crtc->helper_private;
		fb = drm_mode_config_fb(crtc);

		if (!crtc->enabled)
			continue;

		if (!fb) {
			DRM_ERROR("no fb to restore??\n");
			continue;
		}

		drm_fb_helper_restore_lut_atomic(mode_set->crtc);
		funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
					    crtc->y, LEAVE_ATOMIC_MODE_SET);
	}

	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_debug_leave);

/**
 * drm_fb_helper_restore_fbdev_mode - restore fbdev configuration
 * @fb_helper: fbcon to restore
 *
 * This should be called from driver's drm ->lastclose callback
 * when implementing an fbcon on top of kms using this helper. This ensures that
 * the user isn't greeted with a black screen when e.g. X dies.
 */
bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
{
	struct drm_device *dev = fb_helper->dev;
	struct drm_plane *plane;
	bool error = false;
	int i;

	drm_warn_on_modeset_not_all_locked(dev);

	list_for_each_entry(plane, &dev->mode_config.plane_list, head)
		drm_plane_force_disable(plane);

	for (i = 0; i < fb_helper->crtc_count; i++) {
		struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
		struct drm_crtc *crtc = mode_set->crtc;
		int ret;

		if (crtc->funcs->cursor_set) {
			ret = crtc->funcs->cursor_set(crtc, NULL, 0, 0, 0);
			if (ret)
				error = true;
		}

		ret = drm_mode_set_config_internal(mode_set);
		if (ret)
			error = true;
	}
	return error;
}
EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode);

/*
 * restore fbcon display for all kms driver's using this helper, used for sysrq
 * and panic handling.
 */
static bool drm_fb_helper_force_kernel_mode(void)
{
	bool ret, error = false;
	struct drm_fb_helper *helper;

	if (list_empty(&kernel_fb_helper_list))
		return false;

	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
		if (helper->dev->switch_power_state == DRM_SWITCH_POWER_OFF)
			continue;

		ret = drm_fb_helper_restore_fbdev_mode(helper);
		if (ret)
			error = true;
	}
	return error;
}

static int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
			void *panic_str)
{
	/*
	 * It's a waste of time and effort to switch back to text console
	 * if the kernel should reboot before panic messages can be seen.
	 */
	if (panic_timeout < 0)
		return 0;

	pr_err("panic occurred, switching back to text console\n");
	return drm_fb_helper_force_kernel_mode();
}

static struct notifier_block paniced = {
	.notifier_call = drm_fb_helper_panic,
};

static bool drm_fb_helper_is_bound(struct drm_fb_helper *fb_helper)
{
	struct drm_device *dev = fb_helper->dev;
	struct drm_crtc *crtc;
	int bound = 0, crtcs_bound = 0;

	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
		if (crtc->fb)
			crtcs_bound++;
		if (crtc->fb == fb_helper->fb)
			bound++;
	}

	if (bound < crtcs_bound)
		return false;
	return true;
}

#ifdef CONFIG_MAGIC_SYSRQ
static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
{
	bool ret;
	ret = drm_fb_helper_force_kernel_mode();
	if (ret == true)
		DRM_ERROR("Failed to restore crtc configuration\n");
}
static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);

static void drm_fb_helper_sysrq(int dummy1)
{
	schedule_work(&drm_fb_helper_restore_work);
}

static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
	.handler = drm_fb_helper_sysrq,
	.help_msg = "force-fb(V)",
	.action_msg = "Restore framebuffer console",
};
#else
static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
#endif

static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_device *dev = fb_helper->dev;
	struct drm_crtc *crtc;
	struct drm_connector *connector;
	int i, j;

	/*
	 * fbdev->blank can be called from irq context in case of a panic.
	 * Since we already have our own special panic handler which will
	 * restore the fbdev console mode completely, just bail out early.
	 */
	if (oops_in_progress)
		return;

	/*
	 * For each CRTC in this fb, turn the connectors on/off.
	 */
	drm_modeset_lock_all(dev);
	if (!drm_fb_helper_is_bound(fb_helper)) {
		drm_modeset_unlock_all(dev);
		return;
	}

	for (i = 0; i < fb_helper->crtc_count; i++) {
		crtc = fb_helper->crtc_info[i].mode_set.crtc;

		if (!crtc->enabled)
			continue;

		/* Walk the connectors & encoders on this fb turning them on/off */
		for (j = 0; j < fb_helper->connector_count; j++) {
			connector = fb_helper->connector_info[j]->connector;
			connector->funcs->dpms(connector, dpms_mode);
			drm_object_property_set_value(&connector->base,
				dev->mode_config.dpms_property, dpms_mode);
		}
	}
	drm_modeset_unlock_all(dev);
}

/**
 * drm_fb_helper_blank - implementation for ->fb_blank
 * @blank: desired blanking state
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_blank(int blank, struct fb_info *info)
{
	switch (blank) {
	/* Display: On; HSync: On, VSync: On */
	case FB_BLANK_UNBLANK:
		drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
		break;
	/* Display: Off; HSync: On, VSync: On */
	case FB_BLANK_NORMAL:
		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
		break;
	/* Display: Off; HSync: Off, VSync: On */
	case FB_BLANK_HSYNC_SUSPEND:
		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
		break;
	/* Display: Off; HSync: On, VSync: Off */
	case FB_BLANK_VSYNC_SUSPEND:
		drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
		break;
	/* Display: Off; HSync: Off, VSync: Off */
	case FB_BLANK_POWERDOWN:
		drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
		break;
	}
	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_blank);

static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
{
	int i;

	for (i = 0; i < helper->connector_count; i++)
		kfree(helper->connector_info[i]);
	kfree(helper->connector_info);
	for (i = 0; i < helper->crtc_count; i++) {
		kfree(helper->crtc_info[i].mode_set.connectors);
		if (helper->crtc_info[i].mode_set.mode)
			drm_mode_destroy(helper->dev, helper->crtc_info[i].mode_set.mode);
	}
	kfree(helper->crtc_info);
}

/**
 * drm_fb_helper_init - initialize a drm_fb_helper structure
 * @dev: drm device
 * @fb_helper: driver-allocated fbdev helper structure to initialize
 * @crtc_count: maximum number of crtcs to support in this fbdev emulation
 * @max_conn_count: max connector count
 *
 * This allocates the structures for the fbdev helper with the given limits.
 * Note that this won't yet touch the hardware (through the driver interfaces)
 * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
 * to allow driver writes more control over the exact init sequence.
 *
 * Drivers must set fb_helper->funcs before calling
 * drm_fb_helper_initial_config().
 *
 * RETURNS:
 * Zero if everything went ok, nonzero otherwise.
 */
int drm_fb_helper_init(struct drm_device *dev,
		       struct drm_fb_helper *fb_helper,
		       int crtc_count, int max_conn_count)
{
	struct drm_crtc *crtc;
	int i;

	fb_helper->dev = dev;

	INIT_LIST_HEAD(&fb_helper->kernel_fb_list);

	fb_helper->crtc_info = kcalloc(crtc_count, sizeof(struct drm_fb_helper_crtc), GFP_KERNEL);
	if (!fb_helper->crtc_info)
		return -ENOMEM;

	fb_helper->crtc_count = crtc_count;
	fb_helper->connector_info = kcalloc(dev->mode_config.num_connector, sizeof(struct drm_fb_helper_connector *), GFP_KERNEL);
	if (!fb_helper->connector_info) {
		kfree(fb_helper->crtc_info);
		return -ENOMEM;
	}
	fb_helper->connector_count = 0;

	for (i = 0; i < crtc_count; i++) {
		fb_helper->crtc_info[i].mode_set.connectors =
			kcalloc(max_conn_count,
				sizeof(struct drm_connector *),
				GFP_KERNEL);

		if (!fb_helper->crtc_info[i].mode_set.connectors)
			goto out_free;
		fb_helper->crtc_info[i].mode_set.num_connectors = 0;
	}

	i = 0;
	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
		fb_helper->crtc_info[i].mode_set.crtc = crtc;
		i++;
	}

	return 0;
out_free:
	drm_fb_helper_crtc_free(fb_helper);
	return -ENOMEM;
}
EXPORT_SYMBOL(drm_fb_helper_init);

void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
{
	if (!list_empty(&fb_helper->kernel_fb_list)) {
		list_del(&fb_helper->kernel_fb_list);
		if (list_empty(&kernel_fb_helper_list)) {
			pr_info("drm: unregistered panic notifier\n");
			atomic_notifier_chain_unregister(&panic_notifier_list,
							 &paniced);
			unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
		}
	}

	drm_fb_helper_crtc_free(fb_helper);

}
EXPORT_SYMBOL(drm_fb_helper_fini);

static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
		     u16 blue, u16 regno, struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_framebuffer *fb = fb_helper->fb;
	int pindex;

	if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
		u32 *palette;
		u32 value;
		/* place color in psuedopalette */
		if (regno > 16)
			return -EINVAL;
		palette = (u32 *)info->pseudo_palette;
		red >>= (16 - info->var.red.length);
		green >>= (16 - info->var.green.length);
		blue >>= (16 - info->var.blue.length);
		value = (red << info->var.red.offset) |
			(green << info->var.green.offset) |
			(blue << info->var.blue.offset);
		if (info->var.transp.length > 0) {
			u32 mask = (1 << info->var.transp.length) - 1;
			mask <<= info->var.transp.offset;
			value |= mask;
		}
		palette[regno] = value;
		return 0;
	}

	/*
	 * The driver really shouldn't advertise pseudo/directcolor
	 * visuals if it can't deal with the palette.
	 */
	if (WARN_ON(!fb_helper->funcs->gamma_set ||
		    !fb_helper->funcs->gamma_get))
		return -EINVAL;

	pindex = regno;

	if (fb->bits_per_pixel == 16) {
		pindex = regno << 3;

		if (fb->depth == 16 && regno > 63)
			return -EINVAL;
		if (fb->depth == 15 && regno > 31)
			return -EINVAL;

		if (fb->depth == 16) {
			u16 r, g, b;
			int i;
			if (regno < 32) {
				for (i = 0; i < 8; i++)
					fb_helper->funcs->gamma_set(crtc, red,
						green, blue, pindex + i);
			}

			fb_helper->funcs->gamma_get(crtc, &r,
						    &g, &b,
						    pindex >> 1);

			for (i = 0; i < 4; i++)
				fb_helper->funcs->gamma_set(crtc, r,
							    green, b,
							    (pindex >> 1) + i);
		}
	}

	if (fb->depth != 16)
		fb_helper->funcs->gamma_set(crtc, red, green, blue, pindex);
	return 0;
}

/**
 * drm_fb_helper_setcmap - implementation for ->fb_setcmap
 * @cmap: cmap to set
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_device *dev = fb_helper->dev;
	struct drm_crtc_helper_funcs *crtc_funcs;
	u16 *red, *green, *blue, *transp;
	struct drm_crtc *crtc;
	int i, j, rc = 0;
	int start;

	drm_modeset_lock_all(dev);
	if (!drm_fb_helper_is_bound(fb_helper)) {
		drm_modeset_unlock_all(dev);
		return -EBUSY;
	}

	for (i = 0; i < fb_helper->crtc_count; i++) {
		crtc = fb_helper->crtc_info[i].mode_set.crtc;
		crtc_funcs = crtc->helper_private;

		red = cmap->red;
		green = cmap->green;
		blue = cmap->blue;
		transp = cmap->transp;
		start = cmap->start;

		for (j = 0; j < cmap->len; j++) {
			u16 hred, hgreen, hblue, htransp = 0xffff;

			hred = *red++;
			hgreen = *green++;
			hblue = *blue++;

			if (transp)
				htransp = *transp++;

			rc = setcolreg(crtc, hred, hgreen, hblue, start++, info);
			if (rc)
				goto out;
		}
		if (crtc_funcs->load_lut)
			crtc_funcs->load_lut(crtc);
	}
 out:
	drm_modeset_unlock_all(dev);
	return rc;
}
EXPORT_SYMBOL(drm_fb_helper_setcmap);

/**
 * drm_fb_helper_check_var - implementation for ->fb_check_var
 * @var: screeninfo to check
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
			    struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_framebuffer *fb = fb_helper->fb;
	int depth;

	if (var->pixclock != 0 || in_dbg_master())
		return -EINVAL;

	/* Need to resize the fb object !!! */
	if (var->bits_per_pixel > fb->bits_per_pixel ||
	    var->xres > fb->width || var->yres > fb->height ||
	    var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
		DRM_DEBUG("fb userspace requested width/height/bpp is greater than current fb "
			  "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
			  var->xres, var->yres, var->bits_per_pixel,
			  var->xres_virtual, var->yres_virtual,
			  fb->width, fb->height, fb->bits_per_pixel);
		return -EINVAL;
	}

	switch (var->bits_per_pixel) {
	case 16:
		depth = (var->green.length == 6) ? 16 : 15;
		break;
	case 32:
		depth = (var->transp.length > 0) ? 32 : 24;
		break;
	default:
		depth = var->bits_per_pixel;
		break;
	}

	switch (depth) {
	case 8:
		var->red.offset = 0;
		var->green.offset = 0;
		var->blue.offset = 0;
		var->red.length = 8;
		var->green.length = 8;
		var->blue.length = 8;
		var->transp.length = 0;
		var->transp.offset = 0;
		break;
	case 15:
		var->red.offset = 10;
		var->green.offset = 5;
		var->blue.offset = 0;
		var->red.length = 5;
		var->green.length = 5;
		var->blue.length = 5;
		var->transp.length = 1;
		var->transp.offset = 15;
		break;
	case 16:
		var->red.offset = 11;
		var->green.offset = 5;
		var->blue.offset = 0;
		var->red.length = 5;
		var->green.length = 6;
		var->blue.length = 5;
		var->transp.length = 0;
		var->transp.offset = 0;
		break;
	case 24:
		var->red.offset = 16;
		var->green.offset = 8;
		var->blue.offset = 0;
		var->red.length = 8;
		var->green.length = 8;
		var->blue.length = 8;
		var->transp.length = 0;
		var->transp.offset = 0;
		break;
	case 32:
		var->red.offset = 16;
		var->green.offset = 8;
		var->blue.offset = 0;
		var->red.length = 8;
		var->green.length = 8;
		var->blue.length = 8;
		var->transp.length = 8;
		var->transp.offset = 24;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_check_var);

/**
 * drm_fb_helper_set_par - implementation for ->fb_set_par
 * @info: fbdev registered by the helper
 *
 * This will let fbcon do the mode init and is called at initialization time by
 * the fbdev core when registering the driver, and later on through the hotplug
 * callback.
 */
int drm_fb_helper_set_par(struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_device *dev = fb_helper->dev;
	struct fb_var_screeninfo *var = &info->var;
	int ret;
	int i;

	if (var->pixclock != 0) {
		DRM_ERROR("PIXEL CLOCK SET\n");
		return -EINVAL;
	}

	drm_modeset_lock_all(dev);
	for (i = 0; i < fb_helper->crtc_count; i++) {
		ret = drm_mode_set_config_internal(&fb_helper->crtc_info[i].mode_set);
		if (ret) {
			drm_modeset_unlock_all(dev);
			return ret;
		}
	}
	drm_modeset_unlock_all(dev);

	if (fb_helper->delayed_hotplug) {
		fb_helper->delayed_hotplug = false;
		drm_fb_helper_hotplug_event(fb_helper);
	}
	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_set_par);

/**
 * drm_fb_helper_pan_display - implementation for ->fb_pan_display
 * @var: updated screen information
 * @info: fbdev registered by the helper
 */
int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
			      struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	struct drm_device *dev = fb_helper->dev;
	struct drm_mode_set *modeset;
	struct drm_crtc *crtc;
	int ret = 0;
	int i;

	drm_modeset_lock_all(dev);
	if (!drm_fb_helper_is_bound(fb_helper)) {
		drm_modeset_unlock_all(dev);
		return -EBUSY;
	}

	for (i = 0; i < fb_helper->crtc_count; i++) {
		crtc = fb_helper->crtc_info[i].mode_set.crtc;

		modeset = &fb_helper->crtc_info[i].mode_set;

		modeset->x = var->xoffset;
		modeset->y = var->yoffset;

		if (modeset->num_connectors) {
			ret = drm_mode_set_config_internal(modeset);
			if (!ret) {
				info->var.xoffset = var->xoffset;
				info->var.yoffset = var->yoffset;
			}
		}
	}
	drm_modeset_unlock_all(dev);
	return ret;
}
EXPORT_SYMBOL(drm_fb_helper_pan_display);

/*
 * Allocates the backing storage and sets up the fbdev info structure through
 * the ->fb_probe callback and then registers the fbdev and sets up the panic
 * notifier.
 */
static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
					 int preferred_bpp)
{
	int ret = 0;
	int crtc_count = 0;
	int i;
	struct fb_info *info;
	struct drm_fb_helper_surface_size sizes;
	int gamma_size = 0;

	memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
	sizes.surface_depth = 24;
	sizes.surface_bpp = 32;
	sizes.fb_width = (unsigned)-1;
	sizes.fb_height = (unsigned)-1;

	/* if driver picks 8 or 16 by default use that
	   for both depth/bpp */
	if (preferred_bpp != sizes.surface_bpp)
		sizes.surface_depth = sizes.surface_bpp = preferred_bpp;

	/* first up get a count of crtcs now in use and new min/maxes width/heights */
	for (i = 0; i < fb_helper->connector_count; i++) {
		struct drm_fb_helper_connector *fb_helper_conn = fb_helper->connector_info[i];
		struct drm_cmdline_mode *cmdline_mode;

		cmdline_mode = &fb_helper_conn->cmdline_mode;

		if (cmdline_mode->bpp_specified) {
			switch (cmdline_mode->bpp) {
			case 8:
				sizes.surface_depth = sizes.surface_bpp = 8;
				break;
			case 15:
				sizes.surface_depth = 15;
				sizes.surface_bpp = 16;
				break;
			case 16:
				sizes.surface_depth = sizes.surface_bpp = 16;
				break;
			case 24:
				sizes.surface_depth = sizes.surface_bpp = 24;
				break;
			case 32:
				sizes.surface_depth = 24;
				sizes.surface_bpp = 32;
				break;
			}
			break;
		}
	}

	crtc_count = 0;
	for (i = 0; i < fb_helper->crtc_count; i++) {
		struct drm_display_mode *desired_mode;
		desired_mode = fb_helper->crtc_info[i].desired_mode;

		if (desired_mode) {
			if (gamma_size == 0)
				gamma_size = fb_helper->crtc_info[i].mode_set.crtc->gamma_size;
			if (desired_mode->hdisplay < sizes.fb_width)
				sizes.fb_width = desired_mode->hdisplay;
			if (desired_mode->vdisplay < sizes.fb_height)
				sizes.fb_height = desired_mode->vdisplay;
			if (desired_mode->hdisplay > sizes.surface_width)
				sizes.surface_width = desired_mode->hdisplay;
			if (desired_mode->vdisplay > sizes.surface_height)
				sizes.surface_height = desired_mode->vdisplay;
			crtc_count++;
		}
	}

	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
		/* hmm everyone went away - assume VGA cable just fell out
		   and will come back later. */
		DRM_INFO("Cannot find any crtc or sizes - going 1024x768\n");
		sizes.fb_width = sizes.surface_width = 1024;
		sizes.fb_height = sizes.surface_height = 768;
	}

	/* push down into drivers */
	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
	if (ret < 0)
		return ret;

	info = fb_helper->fbdev;

	/*
	 * Set the fb pointer - usually drm_setup_crtcs does this for hotplug
	 * events, but at init time drm_setup_crtcs needs to be called before
	 * the fb is allocated (since we need to figure out the desired size of
	 * the fb before we can allocate it ...). Hence we need to fix things up
	 * here again.
	 */
	for (i = 0; i < fb_helper->crtc_count; i++)
		if (fb_helper->crtc_info[i].mode_set.num_connectors)
			fb_helper->crtc_info[i].mode_set.fb = fb_helper->fb;


	info->var.pixclock = 0;
	if (register_framebuffer(info) < 0)
		return -EINVAL;

	dev_info(fb_helper->dev->dev, "fb%d: %s frame buffer device\n",
			info->node, info->fix.id);

	/* Switch back to kernel console on panic */
	/* multi card linked list maybe */
	if (list_empty(&kernel_fb_helper_list)) {
		dev_info(fb_helper->dev->dev, "registered panic notifier\n");
		atomic_notifier_chain_register(&panic_notifier_list,
					       &paniced);
		register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
	}

	list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);

	return 0;
}

/**
 * drm_fb_helper_fill_fix - initializes fixed fbdev information
 * @info: fbdev registered by the helper
 * @pitch: desired pitch
 * @depth: desired depth
 *
 * Helper to fill in the fixed fbdev information useful for a non-accelerated
 * fbdev emulations. Drivers which support acceleration methods which impose
 * additional constraints need to set up their own limits.
 *
 * Drivers should call this (or their equivalent setup code) from their
 * ->fb_probe callback.
 */
void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
			    uint32_t depth)
{
	info->fix.type = FB_TYPE_PACKED_PIXELS;
	info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
		FB_VISUAL_TRUECOLOR;
	info->fix.mmio_start = 0;
	info->fix.mmio_len = 0;
	info->fix.type_aux = 0;
	info->fix.xpanstep = 1; /* doing it in hw */
	info->fix.ypanstep = 1; /* doing it in hw */
	info->fix.ywrapstep = 0;
	info->fix.accel = FB_ACCEL_NONE;
	info->fix.type_aux = 0;

	info->fix.line_length = pitch;
	return;
}
EXPORT_SYMBOL(drm_fb_helper_fill_fix);

/**
 * drm_fb_helper_fill_var - initalizes variable fbdev information
 * @info: fbdev instance to set up
 * @fb_helper: fb helper instance to use as template
 * @fb_width: desired fb width
 * @fb_height: desired fb height
 *
 * Sets up the variable fbdev metainformation from the given fb helper instance
 * and the drm framebuffer allocated in fb_helper->fb.
 *
 * Drivers should call this (or their equivalent setup code) from their
 * ->fb_probe callback after having allocated the fbdev backing
 * storage framebuffer.
 */
void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
			    uint32_t fb_width, uint32_t fb_height)
{
	struct drm_framebuffer *fb = fb_helper->fb;
	info->pseudo_palette = fb_helper->pseudo_palette;
	info->var.xres_virtual = fb->width;
	info->var.yres_virtual = fb->height;
	info->var.bits_per_pixel = fb->bits_per_pixel;
	info->var.accel_flags = FB_ACCELF_TEXT;
	info->var.xoffset = 0;
	info->var.yoffset = 0;
	info->var.activate = FB_ACTIVATE_NOW;
	info->var.height = -1;
	info->var.width = -1;

	switch (fb->depth) {
	case 8:
		info->var.red.offset = 0;
		info->var.green.offset = 0;
		info->var.blue.offset = 0;
		info->var.red.length = 8; /* 8bit DAC */
		info->var.green.length = 8;
		info->var.blue.length = 8;
		info->var.transp.offset = 0;
		info->var.transp.length = 0;
		break;
	case 15:
		info->var.red.offset = 10;
		info->var.green.offset = 5;
		info->var.blue.offset = 0;
		info->var.red.length = 5;
		info->var.green.length = 5;
		info->var.blue.length = 5;
		info->var.transp.offset = 15;
		info->var.transp.length = 1;
		break;
	case 16:
		info->var.red.offset = 11;
		info->var.green.offset = 5;
		info->var.blue.offset = 0;
		info->var.red.length = 5;
		info->var.green.length = 6;
		info->var.blue.length = 5;
		info->var.transp.offset = 0;
		break;
	case 24:
		info->var.red.offset = 16;
		info->var.green.offset = 8;
		info->var.blue.offset = 0;
		info->var.red.length = 8;
		info->var.green.length = 8;
		info->var.blue.length = 8;
		info->var.transp.offset = 0;
		info->var.transp.length = 0;
		break;
	case 32:
		info->var.red.offset = 16;
		info->var.green.offset = 8;
		info->var.blue.offset = 0;
		info->var.red.length = 8;
		info->var.green.length = 8;
		info->var.blue.length = 8;
		info->var.transp.offset = 24;
		info->var.transp.length = 8;
		break;
	default:
		break;
	}

	info->var.xres = fb_width;
	info->var.yres = fb_height;
}
EXPORT_SYMBOL(drm_fb_helper_fill_var);

static int drm_fb_helper_probe_connector_modes(struct drm_fb_helper *fb_helper,
					       uint32_t maxX,
					       uint32_t maxY)
{
	struct drm_connector *connector;
	int count = 0;
	int i;

	for (i = 0; i < fb_helper->connector_count; i++) {
		connector = fb_helper->connector_info[i]->connector;
		count += connector->funcs->fill_modes(connector, maxX, maxY);
	}

	return count;
}

static struct drm_display_mode *drm_has_preferred_mode(struct drm_fb_helper_connector *fb_connector, int width, int height)
{
	struct drm_display_mode *mode;

	list_for_each_entry(mode, &fb_connector->connector->modes, head) {
		if (drm_mode_width(mode) > width ||
		    drm_mode_height(mode) > height)
			continue;
		if (mode->type & DRM_MODE_TYPE_PREFERRED)
			return mode;
	}
	return NULL;
}

static bool drm_has_cmdline_mode(struct drm_fb_helper_connector *fb_connector)
{
	struct drm_cmdline_mode *cmdline_mode;
	cmdline_mode = &fb_connector->cmdline_mode;
	return cmdline_mode->specified;
}

static struct drm_display_mode *drm_pick_cmdline_mode(struct drm_fb_helper_connector *fb_helper_conn,
						      int width, int height)
{
	struct drm_cmdline_mode *cmdline_mode;
	struct drm_display_mode *mode = NULL;

	cmdline_mode = &fb_helper_conn->cmdline_mode;
	if (cmdline_mode->specified == false)
		return mode;

	/* attempt to find a matching mode in the list of modes
	 *  we have gotten so far, if not add a CVT mode that conforms
	 */
	if (cmdline_mode->rb || cmdline_mode->margins)
		goto create_mode;

	list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
		/* check width/height */
		if (mode->hdisplay != cmdline_mode->xres ||
		    mode->vdisplay != cmdline_mode->yres)
			continue;

		if (cmdline_mode->refresh_specified) {
			if (mode->vrefresh != cmdline_mode->refresh)
				continue;
		}

		if (cmdline_mode->interlace) {
			if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
				continue;
		}
		return mode;
	}

create_mode:
	mode = drm_mode_create_from_cmdline_mode(fb_helper_conn->connector->dev,
						 cmdline_mode);
	list_add(&mode->head, &fb_helper_conn->connector->modes);
	return mode;
}

static bool drm_connector_enabled(struct drm_connector *connector, bool strict)
{
	bool enable;

	if (strict)
		enable = connector->status == connector_status_connected;
	else
		enable = connector->status != connector_status_disconnected;

	return enable;
}

static void drm_enable_connectors(struct drm_fb_helper *fb_helper,
				  bool *enabled)
{
	bool any_enabled = false;
	struct drm_connector *connector;
	int i = 0;

	for (i = 0; i < fb_helper->connector_count; i++) {
		connector = fb_helper->connector_info[i]->connector;
		enabled[i] = drm_connector_enabled(connector, true);
		DRM_DEBUG_KMS("connector %d enabled? %s\n", connector->base.id,
			  enabled[i] ? "yes" : "no");
		any_enabled |= enabled[i];
	}

	if (any_enabled)
		return;

	for (i = 0; i < fb_helper->connector_count; i++) {
		connector = fb_helper->connector_info[i]->connector;
		enabled[i] = drm_connector_enabled(connector, false);
	}
}

static bool drm_target_cloned(struct drm_fb_helper *fb_helper,
			      struct drm_display_mode **modes,
			      bool *enabled, int width, int height)
{
	int count, i, j;
	bool can_clone = false;
	struct drm_fb_helper_connector *fb_helper_conn;
	struct drm_display_mode *dmt_mode, *mode;

	/* only contemplate cloning in the single crtc case */
	if (fb_helper->crtc_count > 1)
		return false;

	count = 0;
	for (i = 0; i < fb_helper->connector_count; i++) {
		if (enabled[i])
			count++;
	}

	/* only contemplate cloning if more than one connector is enabled */
	if (count <= 1)
		return false;

	/* check the command line or if nothing common pick 1024x768 */
	can_clone = true;
	for (i = 0; i < fb_helper->connector_count; i++) {
		if (!enabled[i])
			continue;
		fb_helper_conn = fb_helper->connector_info[i];
		modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
		if (!modes[i]) {
			can_clone = false;
			break;
		}
		for (j = 0; j < i; j++) {
			if (!enabled[j])
				continue;
			if (!drm_mode_equal(modes[j], modes[i]))
				can_clone = false;
		}
	}

	if (can_clone) {
		DRM_DEBUG_KMS("can clone using command line\n");
		return true;
	}

	/* try and find a 1024x768 mode on each connector */
	can_clone = true;
	dmt_mode = drm_mode_find_dmt(fb_helper->dev, 1024, 768, 60, false);

	for (i = 0; i < fb_helper->connector_count; i++) {

		if (!enabled[i])
			continue;

		fb_helper_conn = fb_helper->connector_info[i];
		list_for_each_entry(mode, &fb_helper_conn->connector->modes, head) {
			if (drm_mode_equal(mode, dmt_mode))
				modes[i] = mode;
		}
		if (!modes[i])
			can_clone = false;
	}

	if (can_clone) {
		DRM_DEBUG_KMS("can clone using 1024x768\n");
		return true;
	}
	DRM_INFO("kms: can't enable cloning when we probably wanted to.\n");
	return false;
}

static bool drm_target_preferred(struct drm_fb_helper *fb_helper,
				 struct drm_display_mode **modes,
				 bool *enabled, int width, int height)
{
	struct drm_fb_helper_connector *fb_helper_conn;
	int i;

	for (i = 0; i < fb_helper->connector_count; i++) {
		fb_helper_conn = fb_helper->connector_info[i];

		if (enabled[i] == false)
			continue;

		DRM_DEBUG_KMS("looking for cmdline mode on connector %d\n",
			      fb_helper_conn->connector->base.id);

		/* got for command line mode first */
		modes[i] = drm_pick_cmdline_mode(fb_helper_conn, width, height);
		if (!modes[i]) {
			DRM_DEBUG_KMS("looking for preferred mode on connector %d\n",
				      fb_helper_conn->connector->base.id);
			modes[i] = drm_has_preferred_mode(fb_helper_conn, width, height);
		}
		/* No preferred modes, pick one off the list */
		if (!modes[i] && !list_empty(&fb_helper_conn->connector->modes)) {
			list_for_each_entry(modes[i], &fb_helper_conn->connector->modes, head)
				break;
		}
		DRM_DEBUG_KMS("found mode %s\n", modes[i] ? modes[i]->name :
			  "none");
	}
	return true;
}

static int drm_pick_crtcs(struct drm_fb_helper *fb_helper,
			  struct drm_fb_helper_crtc **best_crtcs,
			  struct drm_display_mode **modes,
			  int n, int width, int height)
{
	int c, o;
	struct drm_device *dev = fb_helper->dev;
	struct drm_connector *connector;
	struct drm_connector_helper_funcs *connector_funcs;
	struct drm_encoder *encoder;
	struct drm_fb_helper_crtc *best_crtc;
	int my_score, best_score, score;
	struct drm_fb_helper_crtc **crtcs, *crtc;
	struct drm_fb_helper_connector *fb_helper_conn;

	if (n == fb_helper->connector_count)
		return 0;

	fb_helper_conn = fb_helper->connector_info[n];
	connector = fb_helper_conn->connector;

	best_crtcs[n] = NULL;
	best_crtc = NULL;
	best_score = drm_pick_crtcs(fb_helper, best_crtcs, modes, n+1, width, height);
	if (modes[n] == NULL)
		return best_score;

	crtcs = kzalloc(dev->mode_config.num_connector *
			sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
	if (!crtcs)
		return best_score;

	my_score = 1;
	if (connector->status == connector_status_connected)
		my_score++;
	if (drm_has_cmdline_mode(fb_helper_conn))
		my_score++;
	if (drm_has_preferred_mode(fb_helper_conn, width, height))
		my_score++;

	connector_funcs = connector->helper_private;
	encoder = connector_funcs->best_encoder(connector);
	if (!encoder)
		goto out;

	/* select a crtc for this connector and then attempt to configure
	   remaining connectors */
	for (c = 0; c < fb_helper->crtc_count; c++) {
		crtc = &fb_helper->crtc_info[c];

		if ((encoder->possible_crtcs & (1 << c)) == 0)
			continue;

		for (o = 0; o < n; o++)
			if (best_crtcs[o] == crtc)
				break;

		if (o < n) {
			/* ignore cloning unless only a single crtc */
			if (fb_helper->crtc_count > 1)
				continue;

			if (!drm_mode_equal(modes[o], modes[n]))
				continue;
		}

		crtcs[n] = crtc;
		memcpy(crtcs, best_crtcs, n * sizeof(struct drm_fb_helper_crtc *));
		score = my_score + drm_pick_crtcs(fb_helper, crtcs, modes, n + 1,
						  width, height);
		if (score > best_score) {
			best_crtc = crtc;
			best_score = score;
			memcpy(best_crtcs, crtcs,
			       dev->mode_config.num_connector *
			       sizeof(struct drm_fb_helper_crtc *));
		}
	}
out:
	kfree(crtcs);
	return best_score;
}

static void drm_setup_crtcs(struct drm_fb_helper *fb_helper)
{
	struct drm_device *dev = fb_helper->dev;
	struct drm_fb_helper_crtc **crtcs;
	struct drm_display_mode **modes;
	struct drm_mode_set *modeset;
	bool *enabled;
	int width, height;
	int i;

	DRM_DEBUG_KMS("\n");

	width = dev->mode_config.max_width;
	height = dev->mode_config.max_height;

	crtcs = kcalloc(dev->mode_config.num_connector,
			sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
	modes = kcalloc(dev->mode_config.num_connector,
			sizeof(struct drm_display_mode *), GFP_KERNEL);
	enabled = kcalloc(dev->mode_config.num_connector,
			  sizeof(bool), GFP_KERNEL);
	if (!crtcs || !modes || !enabled) {
		DRM_ERROR("Memory allocation failed\n");
		goto out;
	}


	drm_enable_connectors(fb_helper, enabled);

	if (!(fb_helper->funcs->initial_config &&
	      fb_helper->funcs->initial_config(fb_helper, crtcs, modes,
					       enabled, width, height))) {
		memset(modes, 0, dev->mode_config.num_connector*sizeof(modes[0]));
		memset(crtcs, 0, dev->mode_config.num_connector*sizeof(crtcs[0]));

		if (!drm_target_cloned(fb_helper,
				       modes, enabled, width, height) &&
		    !drm_target_preferred(fb_helper,
					  modes, enabled, width, height))
			DRM_ERROR("Unable to find initial modes\n");

		DRM_DEBUG_KMS("picking CRTCs for %dx%d config\n",
			      width, height);

		drm_pick_crtcs(fb_helper, crtcs, modes, 0, width, height);
	}

	/* need to set the modesets up here for use later */
	/* fill out the connector<->crtc mappings into the modesets */
	for (i = 0; i < fb_helper->crtc_count; i++) {
		modeset = &fb_helper->crtc_info[i].mode_set;
		modeset->num_connectors = 0;
		modeset->fb = NULL;
	}

	for (i = 0; i < fb_helper->connector_count; i++) {
		struct drm_display_mode *mode = modes[i];
		struct drm_fb_helper_crtc *fb_crtc = crtcs[i];
		modeset = &fb_crtc->mode_set;

		if (mode && fb_crtc) {
			DRM_DEBUG_KMS("desired mode %s set on crtc %d\n",
				      mode->name, fb_crtc->mode_set.crtc->base.id);
			fb_crtc->desired_mode = mode;
			if (modeset->mode)
				drm_mode_destroy(dev, modeset->mode);
			modeset->mode = drm_mode_duplicate(dev,
							   fb_crtc->desired_mode);
			modeset->connectors[modeset->num_connectors++] = fb_helper->connector_info[i]->connector;
			modeset->fb = fb_helper->fb;
		}
	}

	/* Clear out any old modes if there are no more connected outputs. */
	for (i = 0; i < fb_helper->crtc_count; i++) {
		modeset = &fb_helper->crtc_info[i].mode_set;
		if (modeset->num_connectors == 0) {
			BUG_ON(modeset->fb);
			BUG_ON(modeset->num_connectors);
			if (modeset->mode)
				drm_mode_destroy(dev, modeset->mode);
			modeset->mode = NULL;
		}
	}
out:
	kfree(crtcs);
	kfree(modes);
	kfree(enabled);
}

/**
 * drm_fb_helper_initial_config - setup a sane initial connector configuration
 * @fb_helper: fb_helper device struct
 * @bpp_sel: bpp value to use for the framebuffer configuration
 *
 * Scans the CRTCs and connectors and tries to put together an initial setup.
 * At the moment, this is a cloned configuration across all heads with
 * a new framebuffer object as the backing store.
 *
 * Note that this also registers the fbdev and so allows userspace to call into
 * the driver through the fbdev interfaces.
 *
 * This function will call down into the ->fb_probe callback to let
 * the driver allocate and initialize the fbdev info structure and the drm
 * framebuffer used to back the fbdev. drm_fb_helper_fill_var() and
 * drm_fb_helper_fill_fix() are provided as helpers to setup simple default
 * values for the fbdev info structure.
 *
 * RETURNS:
 * Zero if everything went ok, nonzero otherwise.
 */
bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
{
	struct drm_device *dev = fb_helper->dev;
	int count = 0;

	drm_fb_helper_parse_command_line(fb_helper);

	count = drm_fb_helper_probe_connector_modes(fb_helper,
						    dev->mode_config.max_width,
						    dev->mode_config.max_height);
	/*
	 * we shouldn't end up with no modes here.
	 */
	if (count == 0)
		dev_info(fb_helper->dev->dev, "No connectors reported connected with modes\n");

	drm_setup_crtcs(fb_helper);

	return drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
}
EXPORT_SYMBOL(drm_fb_helper_initial_config);

/**
 * drm_fb_helper_hotplug_event - respond to a hotplug notification by
 *                               probing all the outputs attached to the fb
 * @fb_helper: the drm_fb_helper
 *
 * Scan the connectors attached to the fb_helper and try to put together a
 * setup after *notification of a change in output configuration.
 *
 * Called at runtime, takes the mode config locks to be able to check/change the
 * modeset configuration. Must be run from process context (which usually means
 * either the output polling work or a work item launched from the driver's
 * hotplug interrupt).
 *
 * Note that the driver must ensure that this is only called _after_ the fb has
 * been fully set up, i.e. after the call to drm_fb_helper_initial_config.
 *
 * RETURNS:
 * 0 on success and a non-zero error code otherwise.
 */
int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
{
	struct drm_device *dev = fb_helper->dev;
	int count = 0;
	u32 max_width, max_height, bpp_sel;

	if (!fb_helper->fb)
		return 0;

	mutex_lock(&fb_helper->dev->mode_config.mutex);
	if (!drm_fb_helper_is_bound(fb_helper)) {
		fb_helper->delayed_hotplug = true;
		mutex_unlock(&fb_helper->dev->mode_config.mutex);
		return 0;
	}
	DRM_DEBUG_KMS("\n");

	max_width = fb_helper->fb->width;
	max_height = fb_helper->fb->height;
	bpp_sel = fb_helper->fb->bits_per_pixel;

	count = drm_fb_helper_probe_connector_modes(fb_helper, max_width,
						    max_height);
	mutex_unlock(&fb_helper->dev->mode_config.mutex);

	drm_modeset_lock_all(dev);
	drm_setup_crtcs(fb_helper);
	drm_modeset_unlock_all(dev);
	drm_fb_helper_set_par(fb_helper->fbdev);

	return 0;
}
EXPORT_SYMBOL(drm_fb_helper_hotplug_event);

/* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
 * but the module doesn't depend on any fb console symbols.  At least
 * attempt to load fbcon to avoid leaving the system without a usable console.
 */
#if defined(CONFIG_FRAMEBUFFER_CONSOLE_MODULE) && !defined(CONFIG_EXPERT)
static int __init drm_fb_helper_modinit(void)
{
	const char *name = "fbcon";
	struct module *fbcon;

	mutex_lock(&module_mutex);
	fbcon = find_module(name);
	mutex_unlock(&module_mutex);

	if (!fbcon)
		request_module_nowait(name);
	return 0;
}

module_init(drm_fb_helper_modinit);
#endif