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

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 8/26/2022 7:23 AM, Dmitry Baryshkov wrote:
> 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@quicinc.com> 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@linaro.org>
>>>>
>>>> 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.
> 

This explanation makes sense to me. Understood. Hence,

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>


>> 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("");
>>>>>
>>>
>>>
>>>
>