Re: [PATCH 2/3] drm/vc4: Check if plane requires background fill

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Mar 06, 2018 at 02:48:38AM +0100, Stefan Schake wrote:
> Considering a single plane only, we have to enable background color
> when the plane has an alpha format and could be blending from the
> background or when it doesn't cover the entire screen.
> 
> Signed-off-by: Stefan Schake <stschake@gmail.com>
> ---
>  drivers/gpu/drm/vc4/vc4_drv.h   |  6 ++++++
>  drivers/gpu/drm/vc4/vc4_plane.c | 15 ++++++++++++++-
>  2 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index fefa166..7cc6390 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -302,6 +302,12 @@ struct vc4_hvs {
>  
>  struct vc4_plane {
>  	struct drm_plane base;
> +
> +	/* Set when the plane has per-pixel alpha content or does not cover
> +	 * the entire screen. This is a hint to the CRTC that it might need
> +	 * to enable background color fill.
> +	 */
> +	bool needs_bg_fill;

Looks to me like that should really be a bitmask (or something similar)
in the crtc state.

>  };
>  
>  static inline struct vc4_plane *
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index 3d0c8a2..c299e29 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -517,10 +517,12 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  {
>  	struct vc4_dev *vc4 = to_vc4_dev(plane->dev);
>  	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> +	struct vc4_plane *vc4_plane = to_vc4_plane(plane);
>  	struct drm_framebuffer *fb = state->fb;
>  	u32 ctl0_offset = vc4_state->dlist_count;
>  	const struct hvs_format *format = vc4_get_hvs_format(fb->format->format);
>  	int num_planes = drm_format_num_planes(format->drm);
> +	bool covers_screen;
>  	u32 scl0, scl1, pitch0;
>  	u32 lbm_size, tiling;
>  	unsigned long irqflags;
> @@ -625,7 +627,7 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  				      SCALER_POS2_ALPHA_MODE_PIPELINE :
>  				      SCALER_POS2_ALPHA_MODE_FIXED,
>  				      SCALER_POS2_ALPHA_MODE) |
> -			(format->has_alpha ? SCALER_POS2_ALPHA_PREMULT : 0) |
> +			(fb->format->has_alpha ? SCALER_POS2_ALPHA_PREMULT : 0) |
>  			VC4_SET_FIELD(vc4_state->src_w[0], SCALER_POS2_WIDTH) |
>  			VC4_SET_FIELD(vc4_state->src_h[0], SCALER_POS2_HEIGHT));
>  
> @@ -701,6 +703,17 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  	vc4_state->dlist[ctl0_offset] |=
>  		VC4_SET_FIELD(vc4_state->dlist_count, SCALER_CTL0_SIZE);
>  
> +	/* crtc_* are already clipped coordinates. */
> +	covers_screen = vc4_state->crtc_x == 0 && vc4_state->crtc_y == 0 &&
> +			vc4_state->crtc_w == state->crtc->mode.hdisplay &&
> +			vc4_state->crtc_h == state->crtc->mode.vdisplay;
> +	/* Background fill might be necessary when the plane has per-pixel
> +	 * alpha content and blends from the background or does not cover
> +	 * the entire screen.
> +	 */
> +	vc4_plane->needs_bg_fill = fb->format->has_alpha || !covers_screen;
> +
> +
>  	return 0;
>  }
>  
> -- 
> 2.7.4
> 
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-- 
Ville Syrjälä
Intel OTC
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