Re: [PATCH v7 12/18] drm/mediatek: Support "Pre-multiplied" blending in Mixer

From: CK Hu (胡俊光)
Date: Fri May 03 2024 - 05:29:06 EST


Hi, Shawn:

On Thu, 2024-05-02 at 18:38 +0800, Shawn Sung wrote:
> From: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
>
> Support "Pre-multiplied" alpha blending mode in Mixer.
> Before this patch, only the coverage mode is supported.
>
> Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/mediatek/mtk_ethdr.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index 5283e0993ed65..4f043be21ee36 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.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
> @@ -153,7 +155,7 @@ 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 = 0;
> bool replace_src_a = false;
>
> dev_dbg(dev, "%s+ idx:%d", __func__, idx);
> @@ -171,8 +173,12 @@ void mtk_ethdr_layer_config(struct device *dev,
> unsigned int 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);

This looks like plane alpha (the whole video plane use single alpha
value), not related to pre-multiplied blending, so separate this to
another patch.

For no alpha format, you change the setting. If this is bug fix, add
fixes tag.

> +
> + if (state->base.pixel_blend_mode != DRM_MODE_BLEND_COVERAGE)
> + mix_con |= PREMULTI_SOURCE;
> + else
> + mix_con |= NON_PREMULTI_SOURCE;
>
> if (state->base.fb && !state->base.fb->format->has_alpha) {
> /*
> @@ -189,8 +195,7 @@ 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, 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));
> }