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path: root/drivers/gpu/drm/drm_dp_mst_topology.c
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2015-10-21drm: fix mutex leak in drm_dp_get_mst_branch_deviceAdam Richter
In Linux 4.3-rc5, there is an error case in drm_dp_get_branch_device that returns without releasing mgr->lock, resulting a spew of kernel messages about a kernel work function possibly having leaked a mutex and presumably more serious adverse consequences later. This patch changes the error to "goto out" to unlock the mutex before returning. [airlied: grabbed from drm-next as it fixes something we've seen] Signed-off-by: Adam J. Richter <adam_richter2004@yahoo.com> Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-14drm/dp/mst: make mst i2c transfer code more robust.Dave Airlie
This zeroes the msg so no random stack data ends up getting sent, it also limits the function to not accepting > 4 i2c msgs. Cc: stable@vger.kernel.org Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: add some defines for logical/physical portsDave Airlie
This just removes the magic number. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: drop cancel work sync in the mstb destroy path (v2)Dave Airlie
Since 9eb1e57f564d4e6e10991402726cc83fe0b9172f drm/dp/mst: make sure mst_primary mstb is valid in work function we validate the mstb structs in the work function, and doing that takes a reference. So we should never get here with the work function running using the mstb device, only if the work function hasn't run yet or is running for another mstb. So we don't need to sync the work here, this was causing lockdep spew as below. [ +0.000160] ============================================= [ +0.000001] [ INFO: possible recursive locking detected ] [ +0.000002] 3.10.0-320.el7.rhel72.stable.backport.3.x86_64.debug #1 Tainted: G W ------------ [ +0.000001] --------------------------------------------- [ +0.000001] kworker/4:2/1262 is trying to acquire lock: [ +0.000001] ((&mgr->work)){+.+.+.}, at: [<ffffffff810b29a5>] flush_work+0x5/0x2e0 [ +0.000007] but task is already holding lock: [ +0.000001] ((&mgr->work)){+.+.+.}, at: [<ffffffff810b57e4>] process_one_work+0x1b4/0x710 [ +0.000004] other info that might help us debug this: [ +0.000001] Possible unsafe locking scenario: [ +0.000002] CPU0 [ +0.000000] ---- [ +0.000001] lock((&mgr->work)); [ +0.000002] lock((&mgr->work)); [ +0.000001] *** DEADLOCK *** [ +0.000001] May be due to missing lock nesting notation [ +0.000002] 2 locks held by kworker/4:2/1262: [ +0.000001] #0: (events_long){.+.+.+}, at: [<ffffffff810b57e4>] process_one_work+0x1b4/0x710 [ +0.000004] #1: ((&mgr->work)){+.+.+.}, at: [<ffffffff810b57e4>] process_one_work+0x1b4/0x710 [ +0.000003] stack backtrace: [ +0.000003] CPU: 4 PID: 1262 Comm: kworker/4:2 Tainted: G W ------------ 3.10.0-320.el7.rhel72.stable.backport.3.x86_64.debug #1 [ +0.000001] Hardware name: LENOVO 20EGS0R600/20EGS0R600, BIOS GNET71WW (2.19 ) 02/05/2015 [ +0.000008] Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper] [ +0.000001] ffffffff82c26c90 00000000a527b914 ffff88046399bae8 ffffffff816fe04d [ +0.000004] ffff88046399bb58 ffffffff8110f47f ffff880461438000 0001009b840fc003 [ +0.000002] ffff880461438a98 0000000000000000 0000000804dc26e1 ffffffff824a2c00 [ +0.000003] Call Trace: [ +0.000004] [<ffffffff816fe04d>] dump_stack+0x19/0x1b [ +0.000004] [<ffffffff8110f47f>] __lock_acquire+0x115f/0x1250 [ +0.000002] [<ffffffff8110fd49>] lock_acquire+0x99/0x1e0 [ +0.000002] [<ffffffff810b29a5>] ? flush_work+0x5/0x2e0 [ +0.000002] [<ffffffff810b29ee>] flush_work+0x4e/0x2e0 [ +0.000002] [<ffffffff810b29a5>] ? flush_work+0x5/0x2e0 [ +0.000004] [<ffffffff81025905>] ? native_sched_clock+0x35/0x80 [ +0.000002] [<ffffffff81025959>] ? sched_clock+0x9/0x10 [ +0.000002] [<ffffffff810da1f5>] ? local_clock+0x25/0x30 [ +0.000002] [<ffffffff8110dca9>] ? mark_held_locks+0xb9/0x140 [ +0.000003] [<ffffffff810b4ed5>] ? __cancel_work_timer+0x95/0x160 [ +0.000002] [<ffffffff810b4ee8>] __cancel_work_timer+0xa8/0x160 [ +0.000002] [<ffffffff810b4fb0>] cancel_work_sync+0x10/0x20 [ +0.000007] [<ffffffffa0160d17>] drm_dp_destroy_mst_branch_device+0x27/0x120 [drm_kms_helper] [ +0.000006] [<ffffffffa0163968>] drm_dp_mst_link_probe_work+0x78/0xa0 [drm_kms_helper] [ +0.000002] [<ffffffff810b5850>] process_one_work+0x220/0x710 [ +0.000002] [<ffffffff810b57e4>] ? process_one_work+0x1b4/0x710 [ +0.000005] [<ffffffff810b5e5b>] worker_thread+0x11b/0x3a0 [ +0.000003] [<ffffffff810b5d40>] ? process_one_work+0x710/0x710 [ +0.000002] [<ffffffff810beced>] kthread+0xed/0x100 [ +0.000003] [<ffffffff810bec00>] ? insert_kthread_work+0x80/0x80 [ +0.000003] [<ffffffff817121d8>] ret_from_fork+0x58/0x90 v2: add flush_work. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: split connector registration into two parts (v2)Dave Airlie
In order to cache the EDID properly for tiled displays, we need to retrieve it before we register the connector with userspace, otherwise userspace can call get resources and try and get the edid before we've even cached it. This fixes some problems when hotplugging mst monitors, with X/mutter running. As mutter seems to get 0 modes for one of the monitors in the tile. v2: fix warning in radeon handle tile setting in cached path rather than get edid path. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: update the link_address_sent before sending the link address (v3)Dave Airlie
Update the state before sending the msg to close it. v2: reset value if return indicates we haven't send the msg. v3: just clean the code up. Pointed out by Adam J Richter on Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91481 Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: fixup handling hotplug on port removal.Dave Airlie
output ports should always have a connector, unless in the rare case connector allocation fails in the driver. In this case we only need to teardown the pdt, and free the struct, and there is no need to send a hotplug msg. In the case were we add the port to the destroy list we need to send a hotplug if we destroy any connectors, so userspace knows to reprobe stuff. this patch also handles port->connector allocation failing which should be a rare event, but makes the code consistent. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-02drm/dp/mst: don't pass port into the path builder functionDave Airlie
This is unnecessary and it makes it easier to see what is needed from port. also add blank line to make things nicer. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-08-24Merge tag 'v4.2-rc8' into drm-nextDave Airlie
Linux 4.2-rc8 Backmerge required for Intel so they can fix their -next tree up properly.
2015-08-21drm/dp/mst: dump branch OUI in debugfs (v2)Dave Airlie
It appears some MST docks are worse than other, but the only way to know is to see the sw revisions in here, so dump the branch OUI so we can look at the sw revision. v2: Thierry made me feel guilty, so I parsed the branch OUI. Reviewed-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-08-15Merge tag 'topic/drm-fixes-2015-08-14' of ↵Dave Airlie
git://anongit.freedesktop.org/drm-intel into drm-next single MST fixes from Maarten. * tag 'topic/drm-fixes-2015-08-14' of git://anongit.freedesktop.org/drm-intel: drm/dp/mst: Remove port after removing connector.
2015-08-11drm/dp/mst: Remove port after removing connector.Maarten Lankhorst
The port is removed synchronously, but the connector delayed. This causes a use after free which can cause a kernel BUG with slug_debug=FPZU. This is fixed by freeing the port after the connector. This fixes a regression introduced with 6b8eeca65b18ae77e175cc2b6571731f0ee413bf "drm/dp/mst: close deadlock in connector destruction." Cc: stable@vger.kernel.org Cc: Dave Airlie <airlied@redhat.com> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2015-08-04drm/dp-mst: Remove debug WARN_ONDaniel Vetter
Apparently been in there since forever and fairly easy to hit when hotplugging really fast. I can do that since my mst hub has a manual button to flick the hpd line for reprobing. The resulting WARNING spam isn't pretty. Cc: Dave Airlie <airlied@gmail.com> Cc: stable@vger.kernel.org Reviewed-by: Thierry Reding <treding@nvidia.com> Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
2015-06-25drm/dp/mst: close deadlock in connector destruction.Dave Airlie
I've only seen this once, and I failed to capture the lockdep backtrace, but I did some investigations. If we are calling into the MST layer from EDID probing, we have the mode_config mutex held, if during that EDID probing, the MST hub goes away, then we can get a deadlock where the connector destruction function in the driver tries to retake the mode config mutex. This offloads connector destruction to a workqueue, and avoid the subsequenct lock ordering issue. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-06-23drm/dp/mst: take lock around looking up the branch device on hpd irqDave Airlie
If we are doing an MST transaction and we've gotten HPD and we lookup the device from the incoming msg, we should take the mgr lock around it, so that mst_primary and mstb->ports are valid. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-06-23drm/dp/mst: make sure mst_primary mstb is valid in work functionDaniel Vetter
This validates the mst_primary under the lock, and then calls into the check and send function. This makes the code a lot easier to understand the locking rules in. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-03-24Merge tag 'drm-intel-next-2015-03-13-merge' of ↵Dave Airlie
git://anongit.freedesktop.org/drm-intel into drm-next drm-intel-next-2015-03-13-rebased: - EU count report param for gen9+ (Jeff McGee) - piles of pll/wm/... fixes for chv, finally out of preliminary hw support (Ville, Vijay) - gen9 rps support from Akash - more work to move towards atomic from Matt, Ander and others - runtime pm support for skl (Damien) - edp1.4 intermediate link clock support (Sonika) - use frontbuffer tracking for fbc (Paulo) - remove ilk rc6 (John Harrison) - a bunch of smaller things and fixes all over Includes backmerge because git rerere couldn't keep up any more. * tag 'drm-intel-next-2015-03-13-merge' of git://anongit.freedesktop.org/drm-intel: (366 commits) drm/i915: Make sure the primary plane is enabled before reading out the fb state drm/i915: Update DRIVER_DATE to 20150313 drm/i915: Fix vmap_batch page iterator overrun drm/i915: Export total subslice and EU counts drm/i915: redefine WARN_ON_ONCE to include the condition drm/i915/skl: Implement WaDisableHBR2 drm/i915: Remove the preliminary_hw_support shackles from CHV drm/i915: Read CHV_PLL_DW8 from the correct offset drm/i915: Rewrite IVB FDI bifurcation conflict checks drm/i915: Rewrite some some of the FDI lane checks drm/i915/skl: Enable the RPS interrupts programming drm/i915/skl: Enabling processing of Turbo interrupts drm/i915/skl: Updated the i915_frequency_info debugfs function drm/i915: Simplify the way BC bifurcation state consistency is kept drm/i915/skl: Updated the act_freq_mhz_show sysfs function drm/i915/skl: Updated the gen9_enable_rps function drm/i915/skl: Updated the gen6_rps_limits function drm/i915/skl: Restructured the gen6_set_rps_thresholds function drm/i915/skl: Updated the gen6_set_rps function drm/i915/skl: Updated the gen6_init_rps_frequencies function ...
2015-03-19drm/dp_mst: add a function to retrieve vcpi slotsDave Airlie
radeon requires this to get the slots for later filling out a table on every transition. Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2015-03-10drm/mst: fix recursive sleep warning on qlockDaniel Vetter
With drm-next, we can get a backtrace from sleeping with mutex detection. this is due to the callback checking the txmsg state taking the mutex, which can cause a sleep inside a sleep, Daniel went over it and was happy we could drop this mutex in this case. Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-12-08drm/tile: expose the tile property to userspace (v3)Dave Airlie
This takes the tiling info from the connector and exposes it to userspace, as a blob object in a connector property. The contents of the blob is ABI. v2: add property + function documentation. v3: move property setup from previous patch. add boilerplate + fix long line (Daniel) Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-12-08drm/mst: cached EDID for logical ports (v2)Dave Airlie
Logical ports are never going to have EDID changes, they are used for the internal ports on MST monitors. We cache the EDIDs from these to save time at MST probe. v2: drop misplace tile property line, meant for other patch. Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-12-08drm/dp-mst: Remove branches before dropping the referenceDaniel Vetter
When we unplug a dp mst branch we unreference the entire tree from the root towards the leaves. Which is ok, since that's the way the pointers and so also the refcounts go. But when we drop the reference we must make sure that we remove the branches/ports from the lists/pointers before dropping the reference. Otherwise the get_validated functions will still return it instead of returning NULL (which indicates a potentially on-going unplug). The mst branch destroy gets this right for ports: First it deletes the port from the ports list, then it unrefs. But the ports destroy function gets it wrong: First it unrefs, then it drops the ref. Which means a zombie mst branch can still be validate with get_validated_mstb_ref when it shouldn't. Fix this. This should address a backtrace Dave dug out somewhere on unplug: [<ffffffffa00cc262>] drm_dp_mst_get_validated_mstb_ref_locked+0x92/0xa0 [drm_kms_helper] [<ffffffffa00cc211>] drm_dp_mst_get_validated_mstb_ref_locked+0x41/0xa0 [drm_kms_helper] [<ffffffffa00cc2aa>] drm_dp_get_validated_mstb_ref+0x3a/0x60 [drm_kms_helper] [<ffffffffa00cc2fb>] drm_dp_payload_send_msg.isra.14+0x2b/0x100 [drm_kms_helper] [<ffffffffa00cc547>] drm_dp_update_payload_part1+0x177/0x360 [drm_kms_helper] [<ffffffffa015c52e>] intel_mst_disable_dp+0x3e/0x80 [i915] [<ffffffffa013d60b>] haswell_crtc_disable+0x1cb/0x340 [i915] [<ffffffffa0136739>] intel_crtc_control+0x49/0x100 [i915] [<ffffffffa0136857>] intel_crtc_update_dpms+0x67/0x80 [i915] [<ffffffffa013fa59>] intel_connector_dpms+0x59/0x70 [i915] [<ffffffffa015c752>] intel_dp_destroy_mst_connector+0x32/0xc0 [i915] [<ffffffffa00cb44b>] drm_dp_destroy_port+0x6b/0xa0 [drm_kms_helper] [<ffffffffa00cb588>] drm_dp_destroy_mst_branch_device+0x108/0x130 [drm_kms_helper] [<ffffffffa00cb3cd>] drm_dp_port_teardown_pdt+0x3d/0x50 [drm_kms_helper] [<ffffffffa00cdb79>] drm_dp_mst_handle_up_req+0x499/0x540 [drm_kms_helper] [<ffffffff810d9ead>] ? trace_hardirqs_on_caller+0x15d/0x200 [<ffffffffa00cdc73>] drm_dp_mst_hpd_irq+0x53/0xa00 [drm_kms_helper] [<ffffffffa00c7dfb>] ? drm_dp_dpcd_read+0x1b/0x20 [drm_kms_helper] [<ffffffffa0153ed8>] ? intel_dp_dpcd_read_wake+0x38/0x70 [i915] [<ffffffffa015a225>] intel_dp_check_mst_status+0xb5/0x250 [i915] [<ffffffffa015ac71>] intel_dp_hpd_pulse+0x181/0x210 [i915] [<ffffffffa01104f6>] i915_digport_work_func+0x96/0x120 [i915] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-11-14drm/dp/mst: Handle invalid link bandwidth from DPCD gracefullyChris Wilson
Don't BUG out if the link reports an invalid (or plain unknown) bandwidth value, but report the failure and fail gracefully. Fixes a trivial compiler warning in case the BUG is ever compiled away. Link: http://lkml.kernel.org/p/1415785566-12758-1-git-send-email-geert@linux-m68k.org Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Dave Airlie <airlied@redhat.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-11-07Merge tag 'topic/core-stuff-2014-11-05' of ↵Dave Airlie
git://anongit.freedesktop.org/drm-intel into drm-next Just various stuff all over from a bunch of people. Shortlog gives a beter overview, it's really all misc drm patches. * tag 'topic/core-stuff-2014-11-05' of git://anongit.freedesktop.org/drm-intel: drm/edid: add #defines and helpers for ELD drm/dp: Add counters in the drm_dp_aux struct for I2C NACKs and DEFERs drm: Remove compiler BUG_ON() test drm: Fix DRM_FORCE_ON_DIGITAL use drm/gma500: Don't destroy DRM properties in the driver drm/i915: Don't destroy DRM properties in the driver drm: Add a note to drm_property_create() about property lifetime gpu: drm: Fix warning caused by a parameter description in drm_crtc.c drm/dp-helper: Move the legacy helpers to gma500 drm/crtc: Remove duplicated ioctl code drm/crtc: Fix two typos gpu:drm: Fix typo in Documentation/DocBook/drm.xml gpu: drm: drm_dp_mst_topology.c: Fix improper use of strncat drm: drm_err: Remove unnecessary __func__ argument drm: Implement O_NONBLOCK support on /dev/dri/cardN
2014-10-13gpu: drm: drm_dp_mst_topology.c: Fix improper use of strncatRickard Strandqvist
Fixed wrong usage of strncat, switched to strlcpy. While sending the string size to function to reduce the potential for misuse in future. Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-10-13drm/mst: rework payload table allocation to conform better.Dave Airlie
The old code has problems with the Dell MST monitors due to some assumptions I made that weren't true. I initially thought the Virtual Channel Payload IDs had to be in the DPCD table in ascending order, however it appears that assumption is bogus. The old code also assumed it was possible to insert a member into the table and it would move other members up, like it does when you remove table entries, however reality has shown this isn't true. So the new code allocates VCPIs separate from entries in the payload tracking table, and when we remove an entry from the DPCD table, I shuffle the tracking payload entries around in the struct. This appears to make VT switch more robust (still not perfect) with an MST enabled Dell monitor. Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-08-14drm: Don't return 0 for a value used as a denominatorDamien Lespiau
Static analysis will be unhappy if a function can theoretically return 0 and we're trying to divide by that value. Mark that case that cannot occur as a BUG() instead. Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-08-14drm: Docbook fixesDaniel Vetter
Bunch of small leftovers spotted by looking at the make htmldocs output. I've left out dp mst, there's too much amiss there. v2: Also add the missing parameter docbook in the dp mst code - Dave Airlie correctly pointed out that we don't actually want kerneldoc for the missing structure members in header files. Cc: Dave Airlie <airlied@gmail.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-07-22drm/dp: Staticize a couple of DP utility functionsThierry Reding
sparse complains about these functions missing a prototype, but looking closer they aren't (and likely not supposed to be) used outside of this source file, so they can be made static. Signed-off-by: Thierry Reding <treding@nvidia.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-07-18drm/dp-mst-helper: Don't use uninitialized fields of the sideband message headerDamien Lespiau
We could be using uninitialized fields of the header in drm_dp_encode_sideband_msg_hdr(), for instance hdr->somt is set to 1 in the first patcket but never set to 0 otherwise. Always clear the header at the start then. Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-07-18drm/dp-mst-helper: Avoid reading uninitialized valueDamien Lespiau
A static analysis tool tells me that we could try to read an uninitialized 'ret' value. Plug that. Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-07-09drm/mst: fix build with debugfs off.Dave Airlie
seq_file.h was being pulled in via drm_mm.h in that case. Reported-by: Matthew Thode (on irc) Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-07-08drm/helper: add Displayport multi-stream helper (v0.6)Dave Airlie
This is the initial import of the helper for displayport multistream. It consists of a topology manager, init/destroy/set mst state It supports DP 1.2 MST sideband msg protocol handler - via hpd irqs connector detect and edid retrieval interface. It supports i2c device over DP 1.2 sideband msg protocol (EDID reads only) bandwidth manager API via vcpi allocation and payload updating, along with a helper to check the ACT status. Objects: MST topology manager - one per toplevel MST capable GPU port - not sure if this should be higher level again MST branch unit - one instance per plugged branching unit - one at top of hierarchy - others hanging from ports MST port - one port per port reported by branching units, can have MST units hanging from them as well. Changes since initial posting: a) add a mutex responsbile for the queues, it locks the sideband and msg slots, and msgs to transmit state b) add worker to handle connection state change events, for MST device chaining and hotplug c) add a payload spinlock d) add path sideband msg support e) fixup enum path resources transmit f) reduce max dpcd msg to 16, as per DP1.2 spec. g) separate tx queue kicking from irq processing and move irq acking back to drivers. Changes since v0.2: a) reorganise code, b) drop ACT forcing code c) add connector naming interface using path property d) add topology dumper helper e) proper reference counting and lookup for ports and mstbs. f) move tx kicking into a workq g) add aux locking - this should be redone h) split teardown into two parts i) start working on documentation on interface. Changes since v0.3: a) vc payload locking and tracking fixes b) add hotplug callback into driver - replaces crazy return 1 scheme c) txmsg + mst branch device refcount fixes d) don't bail on mst shutdown if device is gone e) change irq handler to take all 4 bytes of SINK_COUNT + ESI vectors f) make DP payload updates timeout longer - observed on docking station redock g) add more info to debugfs dumper Changes since v0.4: a) suspend/resume support b) more debugging in debugfs Changes since v0.5: a) use byte * to avoid unnecessary stack usage b) fix num_sdp_streams interpretation. c) init payload state for unplug events d) remove lenovo dock sink count hack e) drop aux lock - post rebase f) call hotplug on port destroy TODO: misc features Reviewed-by: Todd Previte <tprevite@gmail.com> Signed-off-by: Dave Airlie <airlied@redhat.com>