[PATCH v2 2/2] drm/msm/dp: attach the DP subconnector property

Tue Nov 21 20:10:53 UTC 2023

On 21.11.23 19:50, Abhinav Kumar wrote:
> On 11/21/2023 9:57 AM, Linux regression tracking (Thorsten Leemhuis) wrote:
>> On 15.11.23 19:06, Abhinav Kumar wrote:
>>> On 11/15/2023 12:06 AM, Johan Hovold wrote:
>>>> On Wed, Oct 25, 2023 at 12:23:10PM +0300, Dmitry Baryshkov wrote:
>>>>> While developing and testing the commit bfcc3d8f94f4 ("drm/msm/dp:
>>>>> support setting the DP subconnector type") I had the patch [1] in my
>>>>> tree. I haven't noticed that it was a dependency for the commit in
>>>>> question. Mea culpa.
>>>>
>>>> This also broke boot on the Lenovo ThinkPad X13s.
>>>>
>>>> Would be nice to get this fixed ASAP so that further people don't have
>>>> to debug this known regression.
>>>
>>> I will queue this patch for -fixes rightaway.
>>
>> Thx. I noticed that this fix is still not in -next. I then investigated
>> and I found it was applied on Thursday last week here:
>> https://gitlab.freedesktop.org/drm/msm/-/commits/msm-fixes?ref_type=heads
>>
>> Makes me wonder: when will that patch go to a branch that is included in
>> -next? And when will it move on towards mainline?
> 
> This has been included in a pull request for 6.7-rc3 to the DRM tree and
> shall make it to -next from there.

Ahh, great, thx, I was slowly getting worried.

Ciao, Thorsten

>>>>> Since the patch has not landed yet (and even was not reviewed)
>>>>> and since one of the bridges erroneously uses USB connector type
>>>>> instead
>>>>> of DP, attach the property directly from the MSM DP driver.
>>>>>
>>>>> This fixes the following oops on DP HPD event:
>>>>>
>>>>>    drm_object_property_set_value
>>>>> (drivers/gpu/drm/drm_mode_object.c:288)
>>>>>    dp_display_process_hpd_high
>>>>> (drivers/gpu/drm/msm/dp/dp_display.c:402)
>>>>>    dp_hpd_plug_handle.isra.0 (drivers/gpu/drm/msm/dp/dp_display.c:604)
>>>>>    hpd_event_thread (drivers/gpu/drm/msm/dp/dp_display.c:1110)
>>>>>    kthread (kernel/kthread.c:388)
>>>>>    ret_from_fork (arch/arm64/kernel/entry.S:858)
>>>>
>>>> This only says where the oops happened, it doesn't necessarily in
>>>> itself
>>>> indicate an oops at all or that in this case it's a NULL pointer
>>>> dereference.
>>>>
>>>> On the X13s I'm seeing the NULL deref in a different path during boot,
>>>> and when this happens after a deferred probe (due to the panel lookup
>>>> mess) it hangs the machine, which makes it a bit of a pain to debug:
>>>>
>>>>      Unable to handle kernel NULL pointer dereference at virtual
>>>> address 0000000000000060
>>>>      ...
>>>>      CPU: 4 PID: 57 Comm: kworker/u16:1 Not tainted 6.7.0-rc1 #4
>>>>      Hardware name: Qualcomm QRD, BIOS
>>>> 6.0.220110.BOOT.MXF.1.1-00470-MAKENA-1 01/10/2022
>>>>      ...
>>>>      Call trace:
>>>>       drm_object_property_set_value+0x0/0x88 [drm]
>>>>       dp_display_process_hpd_high+0xa0/0x14c [msm]
>>>>       dp_hpd_plug_handle.constprop.0.isra.0+0x90/0x110 [msm]
>>>>       dp_bridge_atomic_enable+0x184/0x21c [msm]
>>>>       edp_bridge_atomic_enable+0x60/0x94 [msm]
>>>>       drm_atomic_bridge_chain_enable+0x54/0xc8 [drm]
>>>>       drm_atomic_helper_commit_modeset_enables+0x194/0x26c
>>>> [drm_kms_helper]
>>>>       msm_atomic_commit_tail+0x204/0x804 [msm]
>>>>       commit_tail+0xa4/0x18c [drm_kms_helper]
>>>>       drm_atomic_helper_commit+0x19c/0x1b0 [drm_kms_helper]
>>>>       drm_atomic_commit+0xa4/0x104 [drm]
>>>>       drm_client_modeset_commit_atomic+0x22c/0x298 [drm]
>>>>       drm_client_modeset_commit_locked+0x60/0x1c0 [drm]
>>>>       drm_client_modeset_commit+0x30/0x58 [drm]
>>>>       __drm_fb_helper_restore_fbdev_mode_unlocked+0xbc/0xfc
>>>> [drm_kms_helper]
>>>>       drm_fb_helper_set_par+0x30/0x4c [drm_kms_helper]
>>>>       fbcon_init+0x224/0x49c
>>>>       visual_init+0xb0/0x108
>>>>       do_bind_con_driver.isra.0+0x19c/0x38c
>>>>       do_take_over_console+0x140/0x1ec
>>>>       do_fbcon_takeover+0x6c/0xe4
>>>>       fbcon_fb_registered+0x180/0x1f0
>>>>       register_framebuffer+0x19c/0x228
>>>>       __drm_fb_helper_initial_config_and_unlock+0x2e8/0x4e8
>>>> [drm_kms_helper]
>>>>       drm_fb_helper_initial_config+0x3c/0x4c [drm_kms_helper]
>>>>       msm_fbdev_client_hotplug+0x84/0xcc [msm]
>>>>       drm_client_register+0x5c/0xa0 [drm]
>>>>       msm_fbdev_setup+0x94/0x148 [msm]
>>>>       msm_drm_bind+0x3d0/0x42c [msm]
>>>>       try_to_bring_up_aggregate_device+0x1ec/0x2f4
>>>>       __component_add+0xa8/0x194
>>>>       component_add+0x14/0x20
>>>>       dp_display_probe+0x278/0x41c [msm]
>>>>
>>>>> [1] https://patchwork.freedesktop.org/patch/555530/
>>>>>
>>>>> Fixes: bfcc3d8f94f4 ("drm/msm/dp: support setting the DP subconnector
>>>>> type")
>>>>> Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>>>
>>>> Reviewed-by: Johan Hovold <johan+linaro at kernel.org>
>>>> Tested-by: Johan Hovold <johan+linaro at kernel.org>
>>>>
>>>
>>> Thanks !
>>>
>>>> Johan
> 
> 