From 16ef53a93c107392cd652f47251954064fa171e6 Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Tue, 3 Nov 2015 21:00:10 -0500
Subject: drm/nouveau/disp: activate dual link TMDS links only when possible

Without this patch a pixel clock rate above 165 MHz on a TMDS link is
assumed to be dual link. This is true for DVI, but not for HDMI. HDMI
supports no dual link, but it supports pixel clock rates above 165 MHz.
Only activate Dual Link mode when it is actually possible and requested.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
[imirkin: check for hdmi monitor for computing proto, use sor ctrl to
 enable extra config bit]
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index 44e1952..ee97eae 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -1962,10 +1962,17 @@ nv50_sor_mode_set(struct drm_encoder *encoder, struct drm_display_mode *umode,
 	switch (nv_encoder->dcb->type) {
 	case DCB_OUTPUT_TMDS:
 		if (nv_encoder->dcb->sorconf.link & 1) {
-			if (mode->clock < 165000)
-				proto = 0x1;
-			else
-				proto = 0x5;
+			proto = 0x1;
+			/* Only enable dual-link if:
+			 *  - Need to (i.e. rate > 165MHz)
+			 *  - DCB says we can
+			 *  - Not an HDMI monitor, since there's no dual-link
+			 *    on HDMI.
+			 */
+			if (mode->clock >= 165000 &&
+			    nv_encoder->dcb->duallink_possible &&
+			    !drm_detect_hdmi_monitor(nv_connector->edid))
+				proto |= 0x4;
 		} else {
 			proto = 0x2;
 		}
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/gf119.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/gf119.c
index 186fd3a..f031466 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/gf119.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/gf119.c
@@ -158,7 +158,7 @@ exec_clkcmp(struct nv50_disp *disp, int head, int id, u32 pclk, u32 *conf)
 	switch (outp->info.type) {
 	case DCB_OUTPUT_TMDS:
 		*conf = (ctrl & 0x00000f00) >> 8;
-		if (pclk >= 165000)
+		if (*conf == 5)
 			*conf |= 0x0100;
 		break;
 	case DCB_OUTPUT_LVDS:
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
index 32e73a9..4226d21 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
@@ -391,7 +391,7 @@ exec_clkcmp(struct nv50_disp *disp, int head, int id, u32 pclk, u32 *conf)
 		switch (outp->info.type) {
 		case DCB_OUTPUT_TMDS:
 			*conf = (ctrl & 0x00000f00) >> 8;
-			if (pclk >= 165000)
+			if (*conf == 5)
 				*conf |= 0x0100;
 			break;
 		case DCB_OUTPUT_LVDS:
-- 
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