linux-toradex.git/drivers/gpu/drm/msm/dp, branch master

drm/msm/dp: fix link bandwidth check when wide bus is enabled

2026-09-13T21:24:21+00:00

msm_dp_display_mode_valid() halves the pixel clock when either YUV420 or
wide bus is in use, then uses that halved value both for the controller
pixel clock limit and for the DP link bandwidth check.

Only YUV420 halves the data crossing the link. Wide bus widens the
internal DPU to DP interface to two pixels per clock, halving the
controller clock. Every pixel is still transmitted, so the link
bandwidth requirement remains.

As a result, modes needing up to twice the available link bandwidth pass
validation. On the IMDT QCS8550 SBC (rev5 with CYPD6125), where DP runs
over USB-C alt mode where only two lanes are available, 3840x2160@60 was
accepted despite needing 9.6 Gbps against the 8.64 Gbps the link can
carry.

Use a separate link pixel clock that is only halved for YUV420 for the
bandwidth calculation, leaving the wide bus halving to apply solely to
the controller pixel clock limit. With this, 4k@60 is correctly rejected
and 4k@30 selected instead.

Fixes: df9cf852ca30 ("drm/msm/dp: account for widebus and yuv420 during mode validation")
Assisted-by: Claude:claude-opus-5
Signed-off-by: William Bright 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/746145/
Link: https://lore.kernel.org/r/20260812-msm-dp-link-bw-v1-1-b0e3ce1190be@imd-tec.com
[DB: dropped useless comment]
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: skip PUSH_IDLE when the link was never enabled

2026-09-13T21:16:20+00:00

msm_dp_display_atomic_enable() returns early when link training fails,
leaving ->power_on false and the main link down.
msm_dp_display_atomic_disable() nevertheless writes DP_STATE_CTRL_PUSH_IDLE
and waits for an idle-pattern completion that cannot arrive, so every failed
enable is followed by "PUSH_IDLE pattern timedout".

Every other step of the teardown is already gated on that flag:
msm_dp_display_disable(), called from .atomic_post_disable(), returns early
on !power_on. The PUSH_IDLE write is the only one that is not, so the
controller's runtime-PM reference is then dropped without the link having
been taken down.

On glymur (Snapdragon X2 Elite) the consequence is not a warning. The SoC
does not survive it: TrustZone force-stops the SOCCP and ADSP remote
processors and the machine resets silently about 50 ms later, with no oops
and no panic. On an ASUS Zenbook A16 (UX3607OA), whose eDP panel does not
currently train, this reproduces without any compositor or GPU involvement:

  # eDP enable has already failed with "Failed link training (rc=-104)"
  echo 1 > /sys/class/graphics/fb0/blank

  [535.645455] === marker ===
  [535.694833] qcom_q6v5_pas d00000.remoteproc: fatal error received: \
                 sys_m_smsm.c:512:TZ force stop
  [535.694875] remoteproc remoteproc0: crash detected in soccp: type fatal error
  [535.728857] qcom_q6v5_pas 6800000.remoteproc: fatal error received: \
                 sys_m_smsm.c:783:err fatal notification received from TZ
  

Gate the PUSH_IDLE write on ->power_on so the disable path is consistent
with the rest of the teardown. With this applied the same sequence is
harmless and the machine stays up; without it, it resets every time.

The unconditional write dates back to the original DP driver
(c943b4948b58 ("drm/msm/dp: add displayPort driver support")), but the
surrounding code has been restructured several times since, so no Fixes:
tag is offered.

Note that the eDP link-training failure that exposes this on the A16 is a
separate problem in the glymur eDP PHY and is reported separately; this
change is about not damaging the machine when training fails, for whatever
reason.

Tested on ASUS Zenbook A16 (UX3607OA), Snapdragon X2 Elite Extreme, on
linux-next next-20260803 and next-20260807. The machine has since been
running next-20260807 with this patch as its daily driver.

Assisted-by: Anthropic:Claude-Opus-5
Signed-off-by: Jesse Casco 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/745167/
Link: https://lore.kernel.org/r/20260808171325.133041-1-jesse.casco@gmail.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: Drop dev_pm_opp_set_rate(0)

2026-07-31T14:08:01+00:00

dev_pm_opp_set_rate(0) removes the vote specified in required-opps but
does not actually park the clock, making it run without the necessary
power backing. Drop the explicit calls to it.

Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Signed-off-by: Konrad Dybcio 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742781/
Link: https://lore.kernel.org/r/20260728-topic-dpu_power-v1-2-e7783b859a70@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: pass panel to display enable/disable helpers

2026-07-31T14:08:01+00:00

Pass struct msm_dp_panel to the display enable/disable helpers to make
them easier to reuse for MST stream handling.

Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742752/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-14-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: make bridge helpers use dp_display to allow re-use

2026-07-31T14:08:01+00:00

dp_bridge helpers take drm_bridge as an input and extract the
dp_display object to be used in the dp_display module. Rather than
doing it in a roundabout way, directly pass the dp_display object
to these helpers so that the MST bridge can also re-use the same
helpers.

Signed-off-by: Abhinav Kumar 
Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742750/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-13-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: simplify link and clock disable sequence

2026-07-31T14:08:01+00:00

Move the common disable steps out of the sink_count check to make the
flow easier to follow.

No functional change intended.

Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742749/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-12-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: split dp_ctrl_off() into stream and link parts

2026-07-31T14:08:01+00:00

Split dp_ctrl_off() into stream and link parts so that for MST
cases we can control the link and pixel parts separately.

Signed-off-by: Abhinav Kumar 
Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742746/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-11-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: allow dp_ctrl stream APIs to use any panel passed to it

2026-07-31T14:08:01+00:00

With MST, multiple sinks share a single DP controller, so a cached
panel in msm_dp_ctrl_private can no longer represent the per-stream
sink. Drop the cache and pass panel explicitly to all stream-related
dp_ctrl APIs.

Signed-off-by: Abhinav Kumar 
Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742745/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-10-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: re-arrange dp_display_disable() into functional parts

2026-07-31T14:08:01+00:00

dp_display_disable() handles special case of when monitor is
disconnected from the dongle while the dongle stays connected
thereby needing a separate function dp_ctrl_off_link_stream()
for this. However with a slight rework this can still be handled
by keeping common paths same for regular and special case.

Signed-off-by: Abhinav Kumar 
Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742742/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-9-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov

drm/msm/dp: break up dp_display_enable into two parts

2026-07-31T14:08:01+00:00

dp_display_enable() currently re-trains the link if needed and then
enables the pixel clock, programs the controller to start sending the
pixel stream. Split these two parts into prepare/enable APIs, to support
MST bridges_enable insert the MST payloads funcs between enable
stream_clks and program register.

Signed-off-by: Abhinav Kumar 
Signed-off-by: Yongxing Mou 
Reviewed-by: Dmitry Baryshkov 
Patchwork: https://patchwork.freedesktop.org/patch/742740/
Link: https://lore.kernel.org/r/20260728-dp_mstclean-v9-8-f7779fce10f4@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov