linux-kernel - Re: [PATCH] drm/msm: Fix shutdown

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Date:   Wed, 4 May 2022 16:33:30 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     <linux-kernel@...r.kernel.org>, David Airlie <airlied@...ux.ie>,
        <freedreno@...ts.freedesktop.org>, Lv Ruyi <lv.ruyi@....com.cn>,
        "Douglas Anderson" <dianders@...omium.org>,
        <dri-devel@...ts.freedesktop.org>,
        "Bjorn Andersson" <bjorn.andersson@...aro.org>,
        Xu Wang <vulab@...as.ac.cn>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Sean Paul <sean@...rly.run>,
        "Vinod Polimera" <quic_vpolimer@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] drm/msm: Fix shutdown



On 5/4/2022 4:30 PM, Dmitry Baryshkov wrote:
> On Thu, 5 May 2022 at 02:29, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>>
>>
>>
>> On 5/4/2022 3:49 PM, Douglas Anderson wrote:
>>> When rebooting on my sc7280-herobrine based device, I got a
>>> crash. Upon debugging, I found that I was in msm_drv_shutdown() and my
>>> "pdev" was the one associated with mdss_probe().
>>>
>>>   From source, I found that mdss_probe() has the line:
>>>     platform_set_drvdata(pdev, mdss);
>>> ...where "mdss" is of type "struct msm_mdss *".
>>>
>>> Also from source, I saw that in msm_drv_shutdown() we have the line:
>>>     struct msm_drm_private *priv = platform_get_drvdata(pdev);
>>>
>>> This is a mismatch and is the root of the problem.
>>>
>>> Further digging made it apparent that msm_drv_shutdown() is only
>>> supposed to be used for parts of the msm display framework that also
>>> call msm_drv_probe() but mdss_probe() doesn't call
>>> msm_drv_probe(). Let's remove the shutdown functon from msm_mdss.c.
>>>
>>> Digging a little further, code inspection found that two drivers that
>>> use msm_drv_probe() weren't calling msm_drv_shutdown(). Let's add it
>>> to them.
>>>
>>> Fixes: ecb23f2e3009 ("drm/msm: split the main platform driver")
>>> Signed-off-by: Douglas Anderson <dianders@...omium.org>
>>
>> Makes sense to me, and issue should happen everytime we shutdown so not
>> sure how it didnt hit?
>>
>>> ---
>>>
>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c  | 1 +
>>>    drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 1 +
>>>    drivers/gpu/drm/msm/msm_mdss.c           | 1 -
>>>    3 files changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>>> index 143d6643be53..2b9d931474e0 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>>> @@ -1350,6 +1350,7 @@ MODULE_DEVICE_TABLE(of, dpu_dt_match);
>>>    static struct platform_driver dpu_driver = {
>>>        .probe = dpu_dev_probe,
>>>        .remove = dpu_dev_remove,
>>> +     .shutdown = msm_drv_shutdown,
>>>        .driver = {
>>>                .name = "msm_dpu",
>>>                .of_match_table = dpu_dt_match,
>>> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> index 9b7bbc3adb97..3d5621a68f85 100644
>>> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
>>> @@ -1009,6 +1009,7 @@ MODULE_DEVICE_TABLE(of, mdp5_dt_match);
>>>    static struct platform_driver mdp5_driver = {
>>>        .probe = mdp5_dev_probe,
>>>        .remove = mdp5_dev_remove,
>>> +     .shutdown = msm_drv_shutdown,
>>>        .driver = {
>>>                .name = "msm_mdp",
>>>                .of_match_table = mdp5_dt_match,
>>> diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
>>> index 20f154dda9cf..0454a571adf7 100644
>>> --- a/drivers/gpu/drm/msm/msm_mdss.c
>>> +++ b/drivers/gpu/drm/msm/msm_mdss.c
>>> @@ -397,7 +397,6 @@ MODULE_DEVICE_TABLE(of, mdss_dt_match);
>>>    static struct platform_driver mdss_platform_driver = {
>>>        .probe      = mdss_probe,
>>>        .remove     = mdss_remove,
>>> -     .shutdown   = msm_drv_shutdown,
>>
>> Question to doug/dmitry:
>>
>> Now that we removed msm_drv_shutdown, perhaps we should have a
>> mdss_shutdown instead and call msm_mdss_destroy() internally?
> 
> No need to. msm-mdss driver doesn't really need to be shutdown. It
> doesn't setup DMA, it doesn't setup video pipes, etc.

Alright,

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> 
>>
>>>        .driver     = {
>>>                .name   = "msm-mdss",
>>>                .of_match_table = mdss_dt_match,
> 
> 
>