linux-kernel - Re: [PATCH 2/5] drm/mediatek: Support "None" blending in Mixer

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Message-ID: <5cee68d3bee73e034781c8ee8b5ff2c2c045791f.camel@mediatek.com>
Date: Thu, 4 Jul 2024 01:35:31 +0000
From: Shawn Sung (宋孝謙) <Shawn.Sung@...iatek.com>
To: CK Hu (胡俊光) <ck.hu@...iatek.com>,
	"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>, "airlied@...il.com"
	<airlied@...il.com>, "daniel@...ll.ch" <daniel@...ll.ch>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/5] drm/mediatek: Support "None" blending in Mixer

Hi CK,

On Mon, 2024-07-01 at 03:10 +0000, CK Hu (胡俊光) wrote:
> Hi, Shawn:
> 
> On Thu, 2024-06-20 at 01:27 +0800, Hsiao Chien Sung via B4 Relay
> wrote:
> >  	 
> > External email : Please do not click links or open attachments
> > until you have verified the sender or the content.
> >  From: Hsiao Chien Sung <shawn.sung@...iatek.com>
> > 
> > Support "None" alpha blending mode on MediaTek's chips.
> > 
> > Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_ethdr.c | 13 ++++++++++---
> >  1 file changed, 10 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> > b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> > index 36021cb8df62..48b714994492 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>
> > @@ -35,6 +36,7 @@
> >  #define MIX_SRC_L0_ENBIT(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_DCM00x120
> > @@ -175,7 +177,13 @@ void mtk_ethdr_layer_config(struct device
> > *dev, unsigned int idx,
> >  alpha_con |= state->base.alpha & MIXER_ALPHA;
> >  }
> >  
> > -if (state->base.fb && !state->base.fb->format->has_alpha) {
> > +if (state->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE)
> > +alpha_con |= PREMULTI_SOURCE;
> 
> To support DRM_MODE_BLEND_PIXEL_NONE, I think ignore pixel alpha is
> enough. Why need this setting?

Yes, by setting PREMULTI_SOURCE bit, ETHDR will ignore the pixel alpha
of the layer.

Thanks,
Shawn

> 
> Regards,
> CK
> 
> > +else
> > +alpha_con |= NON_PREMULTI_SOURCE;
> > +
> > +if ((state->base.fb && !state->base.fb->format->has_alpha) ||
> > +    state->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE) {
> >  /*
> >   * Mixer doesn't support CONST_BLD mode,
> >   * use a trick to make the output equivalent
> > @@ -191,8 +199,7 @@ 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));
> >  }
> > 
> > -- 
> > Git-146)
> > 
> > 
> >