Re: [PATCH v3 08/11] drm/mediatek: Support alpha blending in VDOSYS1

[CK Hu (胡俊光)]

Hi, Hsiao-chien:

Change the title to Support alpha blending in ethdr.

On Tue, 2023-10-17 at 14:47 +0800, Hsiao Chien Sung wrote:
> Support premultiply and coverage alpha blending modes.
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> ---
>  .../gpu/drm/mediatek/mtk_disp_ovl_adaptor.c   |  2 +-
>  drivers/gpu/drm/mediatek/mtk_ethdr.c          | 48 +++++++++++++++
> ----
>  2 files changed, 39 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> index 8de57a5f5518..b69ac90b2e65 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -156,7 +156,7 @@ void mtk_ovl_adaptor_layer_config(struct device
> *dev, unsigned int idx,
>  	merge = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_MERGE0 +
> idx];
>  	ethdr = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_ETHDR0];
>  
> -	if (!pending->enable) {
> +	if (!pending->enable || !pending->width || !pending->height) {

This is not related to alpha blending, so move to another patch.

>  		mtk_merge_stop_cmdq(merge, cmdq_pkt);
>  		mtk_mdp_rdma_stop(rdma_l, cmdq_pkt);
>  		mtk_mdp_rdma_stop(rdma_r, cmdq_pkt);
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index 73dc4da3ba3b..648e14e85bd0 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -5,6 +5,7 @@
>  
>  #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_device.h>
> @@ -35,6 +36,7 @@
>  #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
> @@ -153,33 +155,59 @@ void mtk_ethdr_layer_config(struct device *dev,
> unsigned int idx,
>  	struct mtk_plane_pending_state *pending = &state->pending;
>  	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;
> +	unsigned int mix_con = NON_PREMULTI_SOURCE;
> +	bool replace_src_a = false;
> +
> +	union format {
> +		u32 raw;
> +		u8 str[5];
> +	} format;

You define this just to print raw, I think you could directly print raw
and drop this.

>  
>  	dev_dbg(dev, "%s+ idx:%d", __func__, idx);
>  
>  	if (idx >= 4)
>  		return;
>  
> -	if (!pending->enable) {
> +	if (!pending->enable || !pending->width || !pending->height) {
> +		/*
> +		 * instead of disabling layer with MIX_SRC_CON directly
> +		 * set the size to 0 to avoid screen shift due to mode
> switch
> +		 */

Is this related to alpha? If no, move this to another patch. If so,
describe more detail why alpha need this change?

>  		mtk_ddp_write(cmdq_pkt, 0, &mixer->cmdq_base, mixer-
> >regs, MIX_L_SRC_SIZE(idx));
>  		return;
>  	}
>  
> -	if (state->base.fb && state->base.fb->format->has_alpha)
> -		alpha_con = MIXER_ALPHA_AEN | MIXER_ALPHA;
> +	mix_con |= MIXER_ALPHA_AEN | (state->base.alpha & MIXER_ALPHA);
> +
> +	if (state->base.pixel_blend_mode != DRM_MODE_BLEND_COVERAGE)
> +		mix_con |= PREMULTI_SOURCE;
> +
> +	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;
> +	}
> +
> +	format.raw = pending->format;
> +
> +	dev_dbg(dev, "L%d: %ux%u(%u,%u)%s: SCA=0x%x(%u), MIX=0x%x\n",
> idx,
> +		pending->width, pending->height, pending->x, pending-
> >y,
> +		format.str, (state->base.alpha & MIXER_ALPHA),
> +		state->base.pixel_blend_mode, mix_con);

I do not like per frame log message. Even it would not print by log
level, it would be record to log buffer and dmesg would show it. So
drop this.

>  
> -	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1, alpha_con ?
> false : true,
> -				  DEFAULT_9BIT_ALPHA,
> +	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1,
> replace_src_a, MIXER_ALPHA,
>  				  pending->x & 1 ?
> MIXER_INX_MODE_EVEN_EXTEND :
>  				  MIXER_INX_MODE_BYPASS, align_width /
> 2 - 1, cmdq_pkt);
>  
>  	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_mask(cmdq_pkt, BIT(idx), &mixer->cmdq_base,
> mixer->regs, MIX_SRC_CON,
> -			   BIT(idx));
> +	mtk_ddp_write(cmdq_pkt, mix_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));

This is not related to alpha, so do not modify this.

Regards,
CK

>  }
>  
>  void mtk_ethdr_config(struct device *dev, unsigned int w,