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

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Date:   Wed, 4 May 2022 16:29:05 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Douglas Anderson <dianders@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     Stephen Boyd <swboyd@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>, Lv Ruyi <lv.ruyi@....com.cn>,
        Sean Paul <sean@...rly.run>,
        Vinod Polimera <quic_vpolimer@...cinc.com>,
        Xu Wang <vulab@...as.ac.cn>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm: Fix shutdown



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?

>   	.driver     = {
>   		.name   = "msm-mdss",
>   		.of_match_table = mdss_dt_match,