Re: [PATCH RFC v4 4/7] drm/atomic: Loosen FB atomic checks

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 30/06/2023 03:25, Jessica Zhang wrote:
> Loosen the requirements for atomic and legacy commit so that, in cases
> where solid fill planes is enabled but no FB is set, the commit can
> still go through.
> 
> This includes adding framebuffer NULL checks in other areas to account
> for FB being NULL when solid fill is enabled.
> 
> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
> ---
>   drivers/gpu/drm/drm_atomic.c        | 14 +++++++-------
>   drivers/gpu/drm/drm_atomic_helper.c | 34 ++++++++++++++++++++--------------
>   drivers/gpu/drm/drm_plane.c         |  8 ++++----
>   include/drm/drm_atomic_helper.h     |  4 ++--
>   include/drm/drm_plane.h             | 28 ++++++++++++++++++++++++++++
>   5 files changed, 61 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 404b984d2d9f..ec9681c25366 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -668,14 +668,14 @@ static int drm_atomic_plane_check(const struct drm_plane_state *old_plane_state,
>   	const struct drm_framebuffer *fb = new_plane_state->fb;
>   	int ret;
>   
> -	/* either *both* CRTC and FB must be set, or neither */
> -	if (crtc && !fb) {
> -		drm_dbg_atomic(plane->dev, "[PLANE:%d:%s] CRTC set but no FB\n",
> +	/* either *both* CRTC and pixel source must be set, or neither */
> +	if (crtc && !drm_plane_has_visible_data(new_plane_state)) {
> +		drm_dbg_atomic(plane->dev, "[PLANE:%d:%s] CRTC set but no visible data\n",
>   			       plane->base.id, plane->name);
>   		return -EINVAL;
> -	} else if (fb && !crtc) {
> -		drm_dbg_atomic(plane->dev, "[PLANE:%d:%s] FB set but no CRTC\n",
> -			       plane->base.id, plane->name);
> +	} else if (drm_plane_has_visible_data(new_plane_state) && !crtc) {
> +		drm_dbg_atomic(plane->dev, "[PLANE:%d:%s] Source %d has visible data but no CRTC\n",
> +			       plane->base.id, plane->name, new_plane_state->pixel_source);
>   		return -EINVAL;
>   	}
>   
> @@ -706,7 +706,7 @@ static int drm_atomic_plane_check(const struct drm_plane_state *old_plane_state,
>   	}
>   
>   
> -	if (fb) {
> +	if (new_plane_state->pixel_source == DRM_PLANE_PIXEL_SOURCE_FB && fb) {
>   		ret = drm_atomic_check_fb(new_plane_state);
>   		if (ret)
>   			return ret;
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 41b8066f61ff..d05ec9ef2b3e 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -864,7 +864,7 @@ int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state,
>   	*src = drm_plane_state_src(plane_state);
>   	*dst = drm_plane_state_dest(plane_state);
>   
> -	if (!fb) {
> +	if (!drm_plane_has_visible_data(plane_state)) {
>   		plane_state->visible = false;
>   		return 0;
>   	}
> @@ -881,25 +881,31 @@ int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state,
>   		return -EINVAL;
>   	}
>   
> -	drm_rect_rotate(src, fb->width << 16, fb->height << 16, rotation);
> +	if (plane_state->pixel_source == DRM_PLANE_PIXEL_SOURCE_FB && fb) {
> +		drm_rect_rotate(src, fb->width << 16, fb->height << 16, rotation);
>   
> -	/* Check scaling */
> -	hscale = drm_rect_calc_hscale(src, dst, min_scale, max_scale);
> -	vscale = drm_rect_calc_vscale(src, dst, min_scale, max_scale);
> -	if (hscale < 0 || vscale < 0) {
> -		drm_dbg_kms(plane_state->plane->dev,
> -			    "Invalid scaling of plane\n");
> -		drm_rect_debug_print("src: ", &plane_state->src, true);
> -		drm_rect_debug_print("dst: ", &plane_state->dst, false);
> -		return -ERANGE;
> +		/* Check scaling */
> +		hscale = drm_rect_calc_hscale(src, dst, min_scale, max_scale);
> +		vscale = drm_rect_calc_vscale(src, dst, min_scale, max_scale);
> +
> +		if (hscale < 0 || vscale < 0) {
> +			drm_dbg_kms(plane_state->plane->dev,
> +					"Invalid scaling of plane\n");
> +			drm_rect_debug_print("src: ", &plane_state->src, true);
> +			drm_rect_debug_print("dst: ", &plane_state->dst, false);
> +			return -ERANGE;
> +		}
>   	}
>   
>   	if (crtc_state->enable)
>   		drm_mode_get_hv_timing(&crtc_state->mode, &clip.x2, &clip.y2);
>   
> -	plane_state->visible = drm_rect_clip_scaled(src, dst, &clip);
> -
> -	drm_rect_rotate_inv(src, fb->width << 16, fb->height << 16, rotation);
> +	if (plane_state->pixel_source == DRM_PLANE_PIXEL_SOURCE_FB && fb) {
> +		plane_state->visible = drm_rect_clip_scaled(src, dst, &clip);
> +		drm_rect_rotate_inv(src, fb->width << 16, fb->height << 16, rotation);
> +	} else if (drm_plane_solid_fill_enabled(plane_state)) {
> +		plane_state->visible = true;
> +	}
>   
>   	if (!plane_state->visible)
>   		/*
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index 24e7998d1731..5f19a27ba182 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -861,8 +861,8 @@ static int __setplane_internal(struct drm_plane *plane,
>   
>   	WARN_ON(drm_drv_uses_atomic_modeset(plane->dev));
>   
> -	/* No fb means shut it down */
> -	if (!fb) {
> +	/* No visible data means shut it down */
> +	if (!drm_plane_has_visible_data(plane->state)) {
>   		plane->old_fb = plane->fb;
>   		ret = plane->funcs->disable_plane(plane, ctx);
>   		if (!ret) {
> @@ -913,8 +913,8 @@ static int __setplane_atomic(struct drm_plane *plane,
>   
>   	WARN_ON(!drm_drv_uses_atomic_modeset(plane->dev));
>   
> -	/* No fb means shut it down */
> -	if (!fb)
> +	/* No visible data means shut it down */
> +	if (!drm_plane_has_visible_data(plane->state))
>   		return plane->funcs->disable_plane(plane, ctx);
>   
>   	/*
> diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
> index 536a0b0091c3..6d97f38ac1f6 100644
> --- a/include/drm/drm_atomic_helper.h
> +++ b/include/drm/drm_atomic_helper.h
> @@ -256,8 +256,8 @@ drm_atomic_plane_disabling(struct drm_plane_state *old_plane_state,
>   	 * Anything else should be considered a bug in the atomic core, so we
>   	 * gently warn about it.
>   	 */
> -	WARN_ON((new_plane_state->crtc == NULL && new_plane_state->fb != NULL) ||
> -		(new_plane_state->crtc != NULL && new_plane_state->fb == NULL));
> +	WARN_ON((new_plane_state->crtc == NULL && drm_plane_has_visible_data(new_plane_state)) ||
> +		(new_plane_state->crtc != NULL && !drm_plane_has_visible_data(new_plane_state)));
>   
>   	return old_plane_state->crtc && !new_plane_state->crtc;
>   }
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index 73fb6cf8a5d9..f893f7a56912 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -998,6 +998,34 @@ static inline struct drm_plane *drm_plane_find(struct drm_device *dev,
>   #define drm_for_each_plane(plane, dev) \
>   	list_for_each_entry(plane, &(dev)->mode_config.plane_list, head)
>   
> +/**
> + * drm_plane_solid_fill_enabled - Check if solid fill is enabled on plane
> + * @state: plane state
> + *
> + * Returns:
> + * Whether the plane has been assigned a solid_fill_blob
> + */
> +static inline bool drm_plane_solid_fill_enabled(struct drm_plane_state *state)
> +{
> +	if (!state)
> +		return false;
> +	return state->pixel_source == DRM_PLANE_PIXEL_SOURCE_COLOR && state->solid_fill_blob;
> +}
> +
> +static inline bool drm_plane_has_visible_data(const struct drm_plane_state *state)
> +{
> +	switch (state->pixel_source) {
> +	case DRM_PLANE_PIXEL_SOURCE_COLOR:
> +		return state->solid_fill_blob != NULL;
> +
> +	default:

I'd say, there should a WARN_ON for the default case and then 
fallthrough to the FB case.

> +		return state->fb != NULL;
> +	}
> +
> +	return false;
> +}
> +
> +
>   bool drm_any_plane_has_format(struct drm_device *dev,
>   			      u32 format, u64 modifier);
>   
> 

-- 
With best wishes
Dmitry