linux-kernel - Re: [PATCH v7 10/18] drm/mediatek: Support constant blending in Mixer

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Date: Fri, 3 May 2024 05:45:35 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: Shawn Sung (宋孝謙) <Shawn.Sung@...iatek.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
CC: "linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bibby Hsieh (謝濟遠) <Bibby.Hsieh@...iatek.com>,
	"jason-ch.chen@...iatek.corp-partner.google.com"
	<jason-ch.chen@...iatek.corp-partner.google.com>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"daniel@...ll.ch" <daniel@...ll.ch>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, "dri-devel@...ts.freedesktop.org"
	<dri-devel@...ts.freedesktop.org>, "airlied@...il.com" <airlied@...il.com>,
	"sean@...rly.run" <sean@...rly.run>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "fshao@...omium.org" <fshao@...omium.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v7 10/18] drm/mediatek: Support constant blending in Mixer

Hi, Shawn:

On Thu, 2024-05-02 at 18:38 +0800, Shawn Sung wrote:
> From: Hsiao Chien Sung <shawn.sung@...iatek.com>
> 
> Support constant blending in Mixer.
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_ethdr.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index 4ffd0a0648613..5283e0993ed65 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -154,6 +154,7 @@ 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 +174,15 @@ 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.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,

In original code, mixer already support constant blending. If !state-
>base.fb->format->has_alpha, alpha_con = 0, and parameter alpha_sel is
set to true. So this patch does not change any behavior. Drop this
patch.

Regards,
CK

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