linux-kernel - Re: [PATCH v2 1/2] drm/msm/dpu1: don't choke on disabling the writeback connector

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Message-ID: <61D52432-DD30-4C43-BD5E-1CC9F84DF5B9@linaro.org>
Date: Wed, 07 Aug 2024 17:44:12 +0700
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Leonard Lausen <leonard@...sen.nl>, Rob Clark <robdclark@...il.com>,
 Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>
CC: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 Jeykumar Sankaran <jsanka@...eaurora.org>, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/2] drm/msm/dpu1: don't choke on disabling the writeback connector

On August 5, 2024 9:27:39 AM GMT+07:00, Leonard Lausen <leonard@...sen.nl> wrote:
>Dear Dmitry,
>
>Thank you for the patch. Unfortunately, the patch triggers a regression with
>respect to DRM CRTC state handling. With the patch applied, suspending and
>resuming a lazor sc7180 with external display connected, looses CRTC state on
>resume and prevents applying a new CRTC state. Without the patch, CRTC state is
>preserved across suspend and resume and it remains possible to change CRTC
>settings after resume. This means the patch regresses the user experience,
>preventing "Night Light" mode to work as expected. I've validated this on
>v6.10.2 vs. v6.10.2 with this patch applied.
>

Could you please clarify, I was under the impression that currently whole suspend/resume is broken, so it's more than a dmesg message.

>While the cause for the bug uncovered by this change is likely separate, given
>it's impact, would it be prudent to delay the application of this patch until
>the related bug is identified and fixed? Otherwise we would be fixing a dmesg
>error message "[dpu error]connector not connected 3" that appears to do no harm
>but thereby break more critical user visible behavior.
>
>Best regards
>Leonard
>
>On 8/2/24 15:47, Dmitry Baryshkov wrote:
>> During suspend/resume process all connectors are explicitly disabled and
>> then reenabled. However resume fails because of the connector_status check:
>> 
>> [ 1185.831970] [dpu error]connector not connected 3
>> 
>> It doesn't make sense to check for the Writeback connected status (and
>> other drivers don't perform such check), so drop the check.
>> 
>> Fixes: 71174f362d67 ("drm/msm/dpu: move writeback's atomic_check to dpu_writeback.c")
>> Cc: stable@...r.kernel.org
>> Reported-by: Leonard Lausen <leonard@...sen.nl>
>> Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/57
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>> ---
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c | 3 ---
>>  1 file changed, 3 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>> index 16f144cbc0c9..8ff496082902 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
>> @@ -42,9 +42,6 @@ static int dpu_wb_conn_atomic_check(struct drm_connector *connector,
>>  	if (!conn_state || !conn_state->connector) {
>>  		DPU_ERROR("invalid connector state\n");
>>  		return -EINVAL;
>> -	} else if (conn_state->connector->status != connector_status_connected) {
>> -		DPU_ERROR("connector not connected %d\n", conn_state->connector->status);
>> -		return -EINVAL;
>>  	}
>>  
>>  	crtc = conn_state->crtc;
>> 
>


-- 
With best wishes
Dmitry