linux-kernel - Re: drm/msm: DisplayPort regressions in 6.8-rc1

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Message-ID: <4737bc92-e4e5-4266-a249-d122f15e7ab9@leemhuis.info>
Date: Wed, 14 Feb 2024 14:18:48 +0100
From: "Linux regression tracking (Thorsten Leemhuis)"
 <regressions@...mhuis.info>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>, Johan Hovold
 <johan@...nel.org>, Rob Clark <robdclark@...il.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Bjorn Andersson <quic_bjorande@...cinc.com>, quic_jesszhan@...cinc.com,
 quic_sbillaka@...cinc.com, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
 regressions@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: drm/msm: DisplayPort regressions in 6.8-rc1

On 13.02.24 19:00, Abhinav Kumar wrote:
> 
> Thanks for the report.
> 
> I do agree that pm runtime eDP driver got merged that time but I think
> the issue is either a combination of that along with DRM aux bridge
> https://patchwork.freedesktop.org/series/122584/ OR just the latter as
> even that went in around the same time.

In that case allow me a stupid question from the cheap seats:

Is there anything affected users can do to help getting us closer to the
real problem? Like testing a specific commit or two before or after the
merge of one of those features for example? That might help to rule out
a few things.

Ciao, Thorsten

> Thats why perhaps this issue was not seen with the chromebooks we tested
> on as they do not use pmic_glink (aux bridge).
> 
> So we will need to debug this on sc8280xp specifically or an equivalent
> device which uses aux bridge.
> 
> On 2/13/2024 3:42 AM, Johan Hovold wrote:
>> Hi,
>>
>> Since 6.8-rc1 the internal eDP display on the Lenovo ThinkPad X13s does
>> not always show up on boot.
>>
>> The logs indicate problems with the runtime PM and eDP rework that went
>> into 6.8-rc1:
>>
>>     [    6.006236] Console: switching to colour dummy device 80x25
>>     [    6.007542] [drm:dpu_kms_hw_init:1048] dpu hardware
>> revision:0x80000000
>>     [    6.007872] [drm:drm_bridge_attach [drm]] *ERROR* failed to
>> attach bridge /soc@...hy@...b000 to encoder TMDS-31: -16
>>     [    6.007934] [drm:dp_bridge_init [msm]] *ERROR* failed to attach
>> panel bridge: -16
>>     [    6.007983] msm_dpu ae01000.display-controller:
>> [drm:msm_dp_modeset_init [msm]] *ERROR* failed to create dp bridge: -16
>>     [    6.008030] [drm:_dpu_kms_initialize_displayport:588] [dpu
>> error]modeset_init failed for DP, rc = -16
>>     [    6.008050] [drm:_dpu_kms_setup_displays:681] [dpu
>> error]initialize_DP failed, rc = -16
>>     [    6.008068] [drm:dpu_kms_hw_init:1153] [dpu error]modeset init
>> failed: -16
>>     [    6.008388] msm_dpu ae01000.display-controller:
>> [drm:msm_drm_kms_init [msm]] *ERROR* kms hw init failed: -16
>>     
>> and this can also manifest itself as a NULL-pointer dereference:
>>
>>     [    7.339447] Unable to handle kernel NULL pointer dereference at
>> virtual address 0000000000000000
>>     
>>     [    7.643705] pc : drm_bridge_attach+0x70/0x1a8 [drm]
>>     [    7.686415] lr : drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
>>     
>>     [    7.769039] Call trace:
>>     [    7.771564]  drm_bridge_attach+0x70/0x1a8 [drm]
>>     [    7.776234]  drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
>>     [    7.781782]  drm_bridge_attach+0x80/0x1a8 [drm]
>>     [    7.786454]  dp_bridge_init+0xa8/0x15c [msm]
>>     [    7.790856]  msm_dp_modeset_init+0x28/0xc4 [msm]
>>     [    7.795617]  _dpu_kms_drm_obj_init+0x19c/0x680 [msm]
>>     [    7.800731]  dpu_kms_hw_init+0x348/0x4c4 [msm]
>>     [    7.805306]  msm_drm_kms_init+0x84/0x324 [msm]
>>     [    7.809891]  msm_drm_bind+0x1d8/0x3a8 [msm]
>>     [    7.814196]  try_to_bring_up_aggregate_device+0x1f0/0x2f8
>>     [    7.819747]  __component_add+0xa4/0x18c
>>     [    7.823703]  component_add+0x14/0x20
>>     [    7.827389]  dp_display_probe+0x47c/0x568 [msm]
>>     [    7.832052]  platform_probe+0x68/0xd8
>>
>> Users have also reported random crashes at boot since 6.8-rc1, and I've
>> been able to trigger hard crashes twice when testing an external display
>> (USB-C/DP), which may also be related to the DP regressions.
>>
>> I've opened an issue here:
>>
>>     https://gitlab.freedesktop.org/drm/msm/-/issues/51
>>
>> but I also want Thorsten's help to track this so that it gets fixed
>> before 6.8 is released.
>>
>> #regzbot introduced: v6.7..v6.8-rc1
>>
>> The following series is likely the culprit:
>>
>>     https://lore.kernel.org/all/1701472789-25951-1-git-send-email-quic_khsieh@quicinc.com/
>>
>> Johan
> 
>