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

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Message-ID: <42B219B7-01DE-47CC-9D31-E27E40C04428@linaro.org>
Date: Wed, 07 Aug 2024 17:46:03 +0700
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>, Rob Clark <robdclark@...il.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,
 Leonard Lausen <leonard@...sen.nl>
Subject: Re: [PATCH v2 1/2] drm/msm/dpu1: don't choke on disabling the writeback connector

On August 6, 2024 2:19:46 AM GMT+07:00, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>
>
>On 8/2/2024 12:47 PM, 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;
>>   	}
>
>For this issue, do we hit the connector->force = DRM_FORCE_OFF path?

It was hit during the suspend/resume, so yes, it is a forced off, but by the different means.

>
>Because otherwise, writeback does not implement .detect() callback today so its always connected.

It is undefined/unkown (3), not connected (1)

>
>But if that was the case how come this error is only for writeback. Even DP has the same connected check in atomic_check()
>
>Change seems fine with me because ideally this seems like a no-op to me because writeback connector is assumed to be always connected but the issue is missing some details here.
>
>>     	crtc = conn_state->crtc;
>> 


-- 
With best wishes
Dmitry