Re: [PATCH v8 12/16] drm/mediatek: Support "Pre-multiplied" blending in Mixer

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Shawn:

On Thu, 2024-06-06 at 17:26 +0800, Shawn Sung wrote:
> From: Hsiao Chien Sung <shawn.sung@mediatek.com>
> 
> Support "Pre-multiplied" alpha blending mode in Mixer.
> Before this patch, only the coverage mode is supported.
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_ethdr.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index bcced62e455d..d01f65819816 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -6,6 +6,7 @@
>  #include <drm/drm_blend.h>
>  #include <drm/drm_fourcc.h>
>  #include <drm/drm_framebuffer.h>
> +#include <drm/drm_blend.h>
>  #include <linux/clk.h>
>  #include <linux/component.h>
>  #include <linux/of.h>
> @@ -36,6 +37,7 @@
>  #define MIX_SRC_L0_EN				BIT(0)
>  #define MIX_L_SRC_CON(n)		(0x28 + 0x18 * (n))
>  #define NON_PREMULTI_SOURCE			(2 << 12)
> +#define PREMULTI_SOURCE				(3 << 12)
>  #define MIX_L_SRC_SIZE(n)		(0x30 + 0x18 * (n))
>  #define MIX_L_SRC_OFFSET(n)		(0x34 + 0x18 * (n))
>  #define MIX_FUNC_DCM0			0x120
> @@ -172,8 +174,12 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
>  		return;
>  	}
>  
> -	if (state->base.fb && state->base.fb->format->has_alpha)
> -		alpha_con = MIXER_ALPHA_AEN | MIXER_ALPHA;
> +	alpha_con |= MIXER_ALPHA_AEN | (state->base.alpha & MIXER_ALPHA);

This is constant alpha, not related to pre-multiplied alpha, so separate it to another patch.

Regards,
CK

> +
> +	if (state->base.pixel_blend_mode != DRM_MODE_BLEND_COVERAGE)
> +		alpha_con |= PREMULTI_SOURCE;
> +	else
> +		alpha_con |= NON_PREMULTI_SOURCE;
>  
>  	if (state->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
>  	    (state->base.fb && !state->base.fb->format->has_alpha)) {
> @@ -191,8 +197,7 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
>  	mtk_ddp_write(cmdq_pkt, pending->height << 16 | align_width, &mixer->cmdq_base,
>  		      mixer->regs, MIX_L_SRC_SIZE(idx));
>  	mtk_ddp_write(cmdq_pkt, offset, &mixer->cmdq_base, mixer->regs, MIX_L_SRC_OFFSET(idx));
> -	mtk_ddp_write_mask(cmdq_pkt, alpha_con, &mixer->cmdq_base, mixer->regs, MIX_L_SRC_CON(idx),
> -			   0x1ff);
> +	mtk_ddp_write(cmdq_pkt, alpha_con, &mixer->cmdq_base, mixer->regs, MIX_L_SRC_CON(idx));
>  	mtk_ddp_write_mask(cmdq_pkt, BIT(idx), &mixer->cmdq_base, mixer->regs, MIX_SRC_CON,
>  			   BIT(idx));
>  }