[PATCH 1/2] drm/msm: provide fb_dirty implemenation

[Dmitry Baryshkov]

On 12/06/2023 13:48, Thomas Zimmermann wrote:
> Hi
> 
> Am 12.06.23 um 11:14 schrieb Marijn Suijten:
>> On 2023-06-12 06:16:15, Dmitry Baryshkov wrote:
>>> Since commit 93e81e38e197 ("drm/fb_helper: Minimize damage-helper
>>> overhead") the drm_fb_helper_funcs::fb_dirty helper is required for
>>> proper dirty/damage processing. The drm/msm driver requires that to
>>> function to let CMD panels to work. Use simplified version of
>>> drm_fbdev_generic_helper_fb_dirty() to fix support for CMD mode panels.
>>>
>>> Reported-by: Degdag Mohamed <degdagmohamed at gmail.com>
>>> Fixes: 93e81e38e197 ("drm/fb_helper: Minimize damage-helper overhead")
>>> Cc: Thomas Zimmermann <tzimmermann at suse.de>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>
>> Thanks, this solves the following warning:
>>
>>      msm_dpu ae01000.display-controller: 
>> drm_WARN_ON_ONCE(!helper->funcs->fb_dirty)
>>      WARNING: CPU: 0 PID: 9 at drivers/gpu/drm/drm_fb_helper.c:381 
>> drm_fb_helper_damage_work+0x1c0/0x20c
>>
>> Reviewed-by: Marijn Suijten <marijn.suijten at somainline.org>
>>
>> Note that drm_fb_helper_funcs documents this as "This callback is
>> optional": is it no longer optional, or are we enabling a damage feature
>> that makes it not-optional?
> 
> It is optional in the sense that most hardware and drivers don't require 
> damage handling. Those that do, also require this callback.

Can we please get this documented? I think it was really optional 
beforehand.

> 
> Best regards
> Thomas
> 
>>
>> - Marijn
>>
>>> ---
>>>   drivers/gpu/drm/msm/msm_fbdev.c | 20 ++++++++++++++++++++
>>>   1 file changed, 20 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/msm/msm_fbdev.c 
>>> b/drivers/gpu/drm/msm/msm_fbdev.c
>>> index fa9c1cbffae3..b933a85420f6 100644
>>> --- a/drivers/gpu/drm/msm/msm_fbdev.c
>>> +++ b/drivers/gpu/drm/msm/msm_fbdev.c
>>> @@ -139,8 +139,28 @@ static int msm_fbdev_create(struct drm_fb_helper 
>>> *helper,
>>>       return ret;
>>>   }
>>> +static int msm_fbdev_fb_dirty(struct drm_fb_helper *helper,
>>> +                  struct drm_clip_rect *clip)
>>> +{
>>> +    struct drm_device *dev = helper->dev;
>>> +    int ret;
>>> +
>>> +    /* Call damage handlers only if necessary */
>>> +    if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
>>> +        return 0;
>>> +
>>> +    if (helper->fb->funcs->dirty) {
>>> +        ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 
>>> 1);
>>> +        if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", 
>>> ret))
>>> +            return ret;
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>>   static const struct drm_fb_helper_funcs msm_fb_helper_funcs = {
>>>       .fb_probe = msm_fbdev_create,
>>> +    .fb_dirty = msm_fbdev_fb_dirty,
>>>   };
>>>   /*
>>> -- 
>>> 2.39.2
>>>
> 

-- 
With best wishes
Dmitry