Re: [PATCH v8 10/16] drm/mediatek: Support "None" 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 "None" alpha blending mode on MediaTek's chips.
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_ethdr.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index 4ffd0a064861..bcced62e455d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2021 MediaTek Inc.
>   */
> 
> +#include <drm/drm_blend.h>
>  #include <drm/drm_fourcc.h>
>  #include <drm/drm_framebuffer.h>
>  #include <linux/clk.h>
> @@ -154,6 +155,7 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
>  	unsigned int offset = (pending->x & 1) << 31 | pending->y << 16 | pending->x;
>  	unsigned int align_width = ALIGN_DOWN(pending->width, 2);
>  	unsigned int alpha_con = 0;
> +	bool replace_src_a = false;
> 
>  	dev_dbg(dev, "%s+ idx:%d", __func__, idx);
> 
> @@ -173,8 +175,16 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
>  	if (state->base.fb && state->base.fb->format->has_alpha)
>  		alpha_con = MIXER_ALPHA_AEN | MIXER_ALPHA;
> 
> -	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1, alpha_con ? false : true,
> -				  DEFAULT_9BIT_ALPHA,
> +	if (state->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
> +	    (state->base.fb && !state->base.fb->format->has_alpha)) {
> +		/*
> +		 * Mixer doesn't support CONST_BLD mode,
> +		 * use a trick to make the output equivalent
> +		 */
> +		replace_src_a = true;
> +	}
> +
> +	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1, replace_src_a, MIXER_ALPHA,

It seems originally replace source alpha with 9 bits constant alpha, but this patch change to 8 bits constant alpha.
Changing from 9 bits to 8 bits is not related to this patch, so separate it to another patch.

Regards,
CK

>  				  pending->x & 1 ? MIXER_INX_MODE_EVEN_EXTEND :
>  				  MIXER_INX_MODE_BYPASS, align_width / 2 - 1, cmdq_pkt);
> 
> --
> 2.18.0
> 
>