linux-kernel - Re: [PATCH] drm/meson: fix shutdown crash when component not probed

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Message-ID: <6a350607-3ccf-1af0-be17-8a31cc937e57@baylibre.com>
Date:   Tue, 25 May 2021 09:19:29 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>
Subject: Re: [PATCH] drm/meson: fix shutdown crash when component not probed

Hi Martin,

On 20/05/2021 22:25, Martin Blumenstingl wrote:
> Hi Neil,
> 
> since this has not received any Reviewed-by yet I tried my best to
> review it myself
> 
> On Fri, Apr 30, 2021 at 10:28 AM Neil Armstrong <narmstrong@...libre.com> wrote:
> [...]
>> --- a/drivers/gpu/drm/meson/meson_drv.c
>> +++ b/drivers/gpu/drm/meson/meson_drv.c
>> @@ -485,11 +485,12 @@ static int meson_probe_remote(struct platform_device *pdev,
>>  static void meson_drv_shutdown(struct platform_device *pdev)
>>  {
>>         struct meson_drm *priv = dev_get_drvdata(&pdev->dev);
> this part made it hard for me because I was wondering where the
> matching dev_set_drvdata call is
> it turns out platform_set_drvdata is used instead, meaning for me it
> would have been easier to understand if platform_get_drvdata was used
> here
> that's however nothing which has changed with this patch

OK sure, indeed, but since it's the same... but yeah it may be an issue if platform_set_drvdata changes.

> 
>> -       struct drm_device *drm = priv->drm;
>>
>> -       DRM_DEBUG_DRIVER("\n");
>> -       drm_kms_helper_poll_fini(drm);
>> -       drm_atomic_helper_shutdown(drm);
>> +       if (!priv)
>> +               return;
>> +
>> +       drm_kms_helper_poll_fini(priv->drm);
>> +       drm_atomic_helper_shutdown(priv->drm);
>>  }
> then this part finally made sense to me (as non-drm person), as
> platform_set_drvdata comes near the end of meson_drv_bind_master (so
> any errors would cause the drvdata to be NULL).
> 
> with this I can also give me:
> Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> in addition to my:
> Tested-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

Thanks !

> 
> Can you please queue this up for -fixes or do we need to ask someone to do it?

Yes, the drm-misc-next & drm-misc-fixes are aleays opened and merged each week in the corresponding drm-next and drm-fixes
branches, so we can push patches at anytime without thinking about the merge window (except drm-misc-fixes merged back with -rc1).

Neil

> 
> 
> Best regards,
> Martin
>