Re: [PATCH v1 1/4] drm/msm/mdp5: stop overriding drvdata

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

On 24/08/2022 20:20, Abhinav Kumar wrote:
> On 8/24/2022 1:29 AM, Dmitry Baryshkov wrote:
> > On Wed, 24 Aug 2022 at 04:25, Abhinav Kumar 
> > <quic_abhinavk@xxxxxxxxxxx> wrote:
> > > On 6/20/2022 2:30 PM, Dmitry Baryshkov wrote:
> > > > The rest of the code expects that master's device drvdata is the
> > > > struct msm_drm_private instance. Do not override the mdp5's drvdata.
> > > >
> > > > Fixes: 6874f48bb8b0 ("drm/msm: make mdp5/dpu devices master 
> > > > components")
> > > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > >
> > > Is this just for consistency across mdp5/dpu drivers?
> > >
> > > What issue was seen if mdp5's platform data is overwritten?
> >
> > I think there was a crash in mdp5_destroy, but I did not capture the
> > log at the moment.
> >
> > As you can see, the mdp5_destroy() expects to get mdp5_kms pointer
> > from the drvdata. However the msm_drv_probe sets the drvdata to
> > msm_drm_private instance. Boom.
>
> Yes, I see that msm_drv_probe sets the drvdata to msm_drm_private.
> But I also see that mdp5_init then sets it to
>
> platform_set_drvdata(pdev, mdp5_kms);
>
> Does this not override it then?

It does. But then the mdp5_pm_ops use msm_pm_prepare()/_complete(). And 
these calls expect the msm_drm_private instance in the drvdata. Maybe I 
stumbled upon this. I don't remember exactly, unfortunately.

> Also seems like the commit which introduced it is present since april, 
> this should have happened even earlier then right?
>
> > > > ---
> > > >    drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 19 +++++++++----------
> > > >    1 file changed, 9 insertions(+), 10 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c 
> > > > b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > > index c668a4b27cc6..daf5b5ca7233 100644
> > > > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > > @@ -203,7 +203,7 @@ static int mdp5_set_split_display(struct msm_kms 
> > > > *kms,
> > > >                                                          
> > > > slave_encoder);
> > > >    }
> > > >
> > > > -static void mdp5_destroy(struct platform_device *pdev);
> > > > +static void mdp5_destroy(struct mdp5_kms *mdp5_kms);
> > > >
> > > >    static void mdp5_kms_destroy(struct msm_kms *kms)
> > > >    {
> > > > @@ -223,7 +223,7 @@ static void mdp5_kms_destroy(struct msm_kms *kms)
> > > >        }
> > > >
> > > >        mdp_kms_destroy(&mdp5_kms->base);
> > > > -     mdp5_destroy(mdp5_kms->pdev);
> > > > +     mdp5_destroy(mdp5_kms);
> > > >    }
> > > >
> > > >    #ifdef CONFIG_DEBUG_FS
> > > > @@ -651,9 +651,8 @@ static int mdp5_kms_init(struct drm_device *dev)
> > > >        return ret;
> > > >    }
> > > >
> > > > -static void mdp5_destroy(struct platform_device *pdev)
> > > > +static void mdp5_destroy(struct mdp5_kms *mdp5_kms)
> > > >    {
> > > > -     struct mdp5_kms *mdp5_kms = platform_get_drvdata(pdev);
> > > >        int i;
> > > >
> > > >        if (mdp5_kms->ctlm)
> > > > @@ -667,7 +666,7 @@ static void mdp5_destroy(struct platform_device 
> > > > *pdev)
> > > >                kfree(mdp5_kms->intfs[i]);
> > > >
> > > >        if (mdp5_kms->rpm_enabled)
> > > > -             pm_runtime_disable(&pdev->dev);
> > > > +             pm_runtime_disable(&mdp5_kms->pdev->dev);
> > > >
> > > >        drm_atomic_private_obj_fini(&mdp5_kms->glob_state);
> > > >        drm_modeset_lock_fini(&mdp5_kms->glob_state_lock);
> > > > @@ -816,8 +815,6 @@ static int mdp5_init(struct platform_device 
> > > > *pdev, struct drm_device *dev)
> > > >                goto fail;
> > > >        }
> > > >
> > > > -     platform_set_drvdata(pdev, mdp5_kms);
> > > > -
> > > >        spin_lock_init(&mdp5_kms->resource_lock);
> > > >
> > > >        mdp5_kms->dev = dev;
> > > > @@ -915,7 +912,7 @@ static int mdp5_init(struct platform_device 
> > > > *pdev, struct drm_device *dev)
> > > >        return 0;
> > > >    fail:
> > > >        if (mdp5_kms)
> > > > -             mdp5_destroy(pdev);
> > > > +             mdp5_destroy(mdp5_kms);
> > > >        return ret;
> > > >    }
> > > >
> > > > @@ -975,7 +972,8 @@ static int mdp5_dev_remove(struct 
> > > > platform_device *pdev)
> > > >    static __maybe_unused int mdp5_runtime_suspend(struct device *dev)
> > > >    {
> > > >        struct platform_device *pdev = to_platform_device(dev);
> > > > -     struct mdp5_kms *mdp5_kms = platform_get_drvdata(pdev);
> > > > +     struct msm_drm_private *priv = platform_get_drvdata(pdev);
> > > > +     struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
> > > >
> > > >        DBG("");
> > > >
> > > > @@ -985,7 +983,8 @@ static __maybe_unused int 
> > > > mdp5_runtime_suspend(struct device *dev)
> > > >    static __maybe_unused int mdp5_runtime_resume(struct device *dev)
> > > >    {
> > > >        struct platform_device *pdev = to_platform_device(dev);
> > > > -     struct mdp5_kms *mdp5_kms = platform_get_drvdata(pdev);
> > > > +     struct msm_drm_private *priv = platform_get_drvdata(pdev);
> > > > +     struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
> > > >
> > > >        DBG("");

--
With best wishes
Dmitry