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

[Marijn Suijten <marijn.suijten@somainline.org>]

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@gmail.com>
> Fixes: 93e81e38e197 ("drm/fb_helper: Minimize damage-helper overhead")
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@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@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?

- 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
>