linux-kernel - Re: [PATCH] drm/arm/malidp: Disable pixel alpha blending for colors that do not have alpha

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Message-ID: <20180112170636.GE11192@e110455-lin.cambridge.arm.com>
Date:   Fri, 12 Jan 2018 17:06:36 +0000
From:   Liviu Dudau <liviu.dudau@....com>
To:     Ayan Halder <ayan.halder@....com>
Cc:     brian.starkey@....com, malidp@...s.arm.com, airlied@...ux.ie,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        nd@....com
Subject: Re: [PATCH] drm/arm/malidp: Disable pixel alpha blending for colors
 that do not have alpha

Hi Ayan,

On Fri, Jan 12, 2018 at 04:33:07PM +0000, Ayan Halder wrote:
> Mali dp needs to disable pixel alpha blending (use layer alpha blending) to
> display color formats that do not contain alpha bits per pixel

In the future, please mention any dependencies on other patches that are
not part of a series. In this case one needs your other patch, "drm: add
drm_format_alpha_bits".

Anyway, looks good to me.

Signed-off-by: Liviu Dudau <liviu.dudau@....com>

Many thanks,
Liviu

> 
> Signed-off-by: Ayan Kumar Halder <ayan.halder@....com>
> ---
>  drivers/gpu/drm/arm/malidp_planes.c | 27 ++++++++++++++++++++++-----
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_planes.c b/drivers/gpu/drm/arm/malidp_planes.c
> index e741979..4d7d564 100644
> --- a/drivers/gpu/drm/arm/malidp_planes.c
> +++ b/drivers/gpu/drm/arm/malidp_planes.c
> @@ -35,6 +35,9 @@
>  #define   LAYER_COMP_MASK		(0x3 << 12)
>  #define   LAYER_COMP_PIXEL		(0x3 << 12)
>  #define   LAYER_COMP_PLANE		(0x2 << 12)
> +#define   LAYER_ALPHA_OFFSET	(16)
> +#define   LAYER_ALPHA_MASK		(0xff)
> +#define	  LAYER_ALPHA(x)		(((x) & LAYER_ALPHA_MASK) << LAYER_ALPHA_OFFSET)
>  #define MALIDP_LAYER_COMPOSE		0x008
>  #define MALIDP_LAYER_SIZE		0x00c
>  #define   LAYER_H_VAL(x)		(((x) & 0x1fff) << 0)
> @@ -268,6 +271,7 @@ static void malidp_de_plane_update(struct drm_plane *plane,
>  	struct malidp_plane_state *ms = to_malidp_plane_state(plane->state);
>  	u32 src_w, src_h, dest_w, dest_h, val;
>  	int i;
> +	u8 alpha_bits = plane->state->fb->format->alpha;
>  
>  	mp = to_malidp_plane(plane);
>  
> @@ -319,12 +323,25 @@ static void malidp_de_plane_update(struct drm_plane *plane,
>  	if (plane->state->rotation & DRM_MODE_REFLECT_Y)
>  		val |= LAYER_V_FLIP;
>  
> -	/*
> -	 * always enable pixel alpha blending until we have a way to change
> -	 * blend modes
> -	 */
>  	val &= ~LAYER_COMP_MASK;
> -	val |= LAYER_COMP_PIXEL;
> +	if (alpha_bits > 0) {
> +
> +		/*
> +		 * always enable pixel alpha blending until we have a way to change
> +		 * blend modes
> +		 */
> +		val |= LAYER_COMP_PIXEL;
> +	} else {
> +
> +		/*
> +		 * do not enable pixel alpha blending as the color channel does not
> +		 * have any alpha information
> +		 */
> +		val |= LAYER_COMP_PLANE;
> +
> +		/* Set layer alpha coefficient to 0xff ie fully opaque */
> +		val |= LAYER_ALPHA(0xff);
> +	}
>  
>  	val &= ~LAYER_FLOWCFG(LAYER_FLOWCFG_MASK);
>  	if (plane->state->crtc) {
> -- 
> 2.7.4
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
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