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

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Date:   Thu, 5 May 2022 02:30:54 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        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 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.

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



-- 
With best wishes
Dmitry