[PATCH 2/5] drm/mediatek: Support "None" blending in Mixer

[CK Hu (胡俊光)]

Hi, Shawn:

On Thu, 2024-07-04 at 01:35 +0000, Shawn Sung (宋孝謙) wrote:
> 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 at mediatek.com>
> > > 
> > > Support "None" alpha blending mode on MediaTek's chips.
> > > 
> > > Signed-off-by: Hsiao Chien Sung <shawn.sung at mediatek.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.

In the later code, replace_src_a would be set to true.
I think replace_src_a is enough to implement DRM_MODE_BLEND_PIXEL_NONE.
So it's not necessary to set PREMULTI_SOURCE.

Regards,
CK

> 
> 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)
> > > 
> > > 
> > >