Re: [PATCH v4 06/17] drm/mediatek: Support alpha blending in OVL

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Hsiao-chien:

On Tue, 2023-12-12 at 20:19 +0800, Hsiao Chien Sung wrote:
> Support premultiply and coverage alpha blending in
> Overlay.

Describe what kind of alpha blending already support for cursor plane.
And separate premultiply alpha and coverage alpha to two patches.

> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 73 +++++++++++++++++----
> ----
>  1 file changed, 51 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index 5aaf4342cdbd..66074c2d917c 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -39,6 +39,7 @@
>  #define DISP_REG_OVL_PITCH_MSB(n)		(0x0040 + 0x20 * (n))
>  #define OVL_PITCH_MSB_2ND_SUBBUF			BIT(16)
>  #define DISP_REG_OVL_PITCH(n)			(0x0044 + 0x20
> * (n))
> +#define OVL_CONST_BLEND					BIT(28)
>  #define DISP_REG_OVL_RDMA_CTRL(n)		(0x00c0 + 0x20 * (n))
>  #define DISP_REG_OVL_RDMA_GMC(n)		(0x00c8 + 0x20 * (n))
>  #define DISP_REG_OVL_ADDR_MT2701		0x0040
> @@ -52,13 +53,16 @@
>  #define GMC_THRESHOLD_HIGH	((1 << GMC_THRESHOLD_BITS) / 4)
>  #define GMC_THRESHOLD_LOW	((1 << GMC_THRESHOLD_BITS) / 8)
>  
> -#define OVL_CON_BYTE_SWAP	BIT(24)
> -#define OVL_CON_MTX_YUV_TO_RGB	(6 << 16)
> -#define OVL_CON_CLRFMT_RGB	(1 << 12)
> -#define OVL_CON_CLRFMT_RGBA8888	(2 << 12)
> -#define OVL_CON_CLRFMT_ARGB8888	(3 << 12)
> -#define OVL_CON_CLRFMT_UYVY	(4 << 12)
> -#define OVL_CON_CLRFMT_YUYV	(5 << 12)
> +#define OVL_CON_CLRFMT_MAN		BIT(23)
> +#define OVL_CON_BYTE_SWAP		BIT(24)
> +#define OVL_CON_RGB_SWAP		BIT(25)
> +#define OVL_CON_CLRFMT_RGB		(1 << 12)
> +#define OVL_CON_CLRFMT_RGBA8888		(2 << 12)
> +#define OVL_CON_CLRFMT_ARGB8888		(3 << 12)
> +#define OVL_CON_CLRFMT_PARGB8888	(OVL_CON_CLRFMT_ARGB8888 |
> OVL_CON_CLRFMT_MAN)
> +#define OVL_CON_CLRFMT_UYVY		(4 << 12)
> +#define OVL_CON_CLRFMT_YUYV		(5 << 12)
> +#define OVL_CON_MTX_YUV_TO_RGB		(6 << 16)
>  #define OVL_CON_CLRFMT_RGB565(ovl)	((ovl)->data->fmt_rgb565_is_0 ?
> \
>  					0 : OVL_CON_CLRFMT_RGB)
>  #define OVL_CON_CLRFMT_RGB888(ovl)	((ovl)->data->fmt_rgb565_is_0 ?
> \
> @@ -208,14 +212,12 @@ void mtk_ovl_clk_disable(struct device *dev)
>  void mtk_ovl_start(struct device *dev)
>  {
>  	struct mtk_disp_ovl *ovl = dev_get_drvdata(dev);
> +	unsigned int reg = readl(ovl->regs +
> DISP_REG_OVL_DATAPATH_CON);
>  
> -	if (ovl->data->smi_id_en) {
> -		unsigned int reg;
> +	if (ovl->data->smi_id_en)
> +		reg |= OVL_LAYER_SMI_ID_EN;
>  
> -		reg = readl(ovl->regs + DISP_REG_OVL_DATAPATH_CON);
> -		reg = reg | OVL_LAYER_SMI_ID_EN;
> -		writel_relaxed(reg, ovl->regs +
> DISP_REG_OVL_DATAPATH_CON);
> -	}
> +	writel_relaxed(reg, ovl->regs + DISP_REG_OVL_DATAPATH_CON);

Nothing change in this function, so drop this modification.

>  	writel_relaxed(0x1, ovl->regs + DISP_REG_OVL_EN);
>  }
>  
> @@ -274,7 +276,13 @@ void mtk_ovl_config(struct device *dev, unsigned
> int w,
>  	if (w != 0 && h != 0)
>  		mtk_ddp_write_relaxed(cmdq_pkt, h << 16 | w, &ovl-
> >cmdq_reg, ovl->regs,
>  				      DISP_REG_OVL_ROI_SIZE);
> -	mtk_ddp_write_relaxed(cmdq_pkt, 0x0, &ovl->cmdq_reg, ovl->regs, 
> DISP_REG_OVL_ROI_BGCLR);
> +
> +	/*
> +	 * The background color should be opaque black (ARGB),
> +	 * otherwise there will be no effect with alpha blend
> +	 */
> +	mtk_ddp_write_relaxed(cmdq_pkt, 0xff000000, &ovl->cmdq_reg,
> +			      ovl->regs, DISP_REG_OVL_ROI_BGCLR);

If cursor plane also has this problem, separate this to a bug-fix
patch. If only new alpha blending mode has this problem, describe more
detail why new blending mode has this problem.

Regards,
CK

>  
>  	mtk_ddp_write(cmdq_pkt, 0x1, &ovl->cmdq_reg, ovl->regs,
> DISP_REG_OVL_RST);
>  	mtk_ddp_write(cmdq_pkt, 0x0, &ovl->cmdq_reg, ovl->regs,
> DISP_REG_OVL_RST);
> @@ -357,7 +365,8 @@ void mtk_ovl_layer_off(struct device *dev,
> unsigned int idx,
>  		      DISP_REG_OVL_RDMA_CTRL(idx));
>  }
>  
> -static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl,
> unsigned int fmt)
> +static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl,
> unsigned int fmt,
> +				    unsigned int blend_mode)
>  {
>  	/* The return value in switch "MEM_MODE_INPUT_FORMAT_XXX"
>  	 * is defined in mediatek HW data sheet.
> @@ -376,18 +385,30 @@ static unsigned int ovl_fmt_convert(struct
> mtk_disp_ovl *ovl, unsigned int fmt)
>  		return OVL_CON_CLRFMT_RGB888(ovl) | OVL_CON_BYTE_SWAP;
>  	case DRM_FORMAT_RGBX8888:
>  	case DRM_FORMAT_RGBA8888:
> -		return OVL_CON_CLRFMT_ARGB8888;
> +		return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> +		       OVL_CON_CLRFMT_ARGB8888 :
> +		       OVL_CON_CLRFMT_PARGB8888;
>  	case DRM_FORMAT_BGRX8888:
>  	case DRM_FORMAT_BGRA8888:
> +		return OVL_CON_BYTE_SWAP |
> +		       (blend_mode == DRM_MODE_BLEND_COVERAGE ?
> +		       OVL_CON_CLRFMT_ARGB8888 :
> +		       OVL_CON_CLRFMT_PARGB8888);
>  	case DRM_FORMAT_BGRA1010102:
>  		return OVL_CON_CLRFMT_ARGB8888 | OVL_CON_BYTE_SWAP;
>  	case DRM_FORMAT_XRGB8888:
>  	case DRM_FORMAT_ARGB8888:
> +		return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> +		       OVL_CON_CLRFMT_RGBA8888 :
> +		       OVL_CON_CLRFMT_PARGB8888;
>  	case DRM_FORMAT_ARGB2101010:
>  		return OVL_CON_CLRFMT_RGBA8888;
>  	case DRM_FORMAT_XBGR8888:
>  	case DRM_FORMAT_ABGR8888:
> -		return OVL_CON_CLRFMT_RGBA8888 | OVL_CON_BYTE_SWAP;
> +		return OVL_CON_RGB_SWAP |
> +		       (blend_mode == DRM_MODE_BLEND_COVERAGE ?
> +		       OVL_CON_CLRFMT_RGBA8888 :
> +		       OVL_CON_CLRFMT_PARGB8888);
>  	case DRM_FORMAT_UYVY:
>  		return OVL_CON_CLRFMT_UYVY | OVL_CON_MTX_YUV_TO_RGB;
>  	case DRM_FORMAT_YUYV:
> @@ -408,6 +429,8 @@ void mtk_ovl_layer_config(struct device *dev,
> unsigned int idx,
>  	unsigned int fmt = pending->format;
>  	unsigned int offset = (pending->y << 16) | pending->x;
>  	unsigned int src_size = (pending->height << 16) | pending-
> >width;
> +	unsigned int blend_mode = state->base.pixel_blend_mode;
> +	unsigned int ignore_pixel_alpha = 0;
>  	unsigned int con;
>  	bool is_afbc = pending->modifier != DRM_FORMAT_MOD_LINEAR;
>  	union overlay_pitch {
> @@ -425,9 +448,15 @@ void mtk_ovl_layer_config(struct device *dev,
> unsigned int idx,
>  		return;
>  	}
>  
> -	con = ovl_fmt_convert(ovl, fmt);
> -	if (state->base.fb && state->base.fb->format->has_alpha)
> -		con |= OVL_CON_AEN | OVL_CON_ALPHA;
> +	con = ovl_fmt_convert(ovl, fmt, blend_mode);
> +	if (state->base.fb) {
> +		con |= OVL_CON_AEN;
> +		con |= state->base.alpha & OVL_CON_ALPHA;
> +	}
> +
> +	if (blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
> +	    (state->base.fb && !state->base.fb->format->has_alpha))
> +		ignore_pixel_alpha = OVL_CONST_BLEND;
>  
>  	if (pending->rotation & DRM_MODE_REFLECT_Y) {
>  		con |= OVL_CON_VIRT_FLIP;
> @@ -444,8 +473,8 @@ void mtk_ovl_layer_config(struct device *dev,
> unsigned int idx,
>  
>  	mtk_ddp_write_relaxed(cmdq_pkt, con, &ovl->cmdq_reg, ovl->regs,
>  			      DISP_REG_OVL_CON(idx));
> -	mtk_ddp_write_relaxed(cmdq_pkt, overlay_pitch.split_pitch.lsb,
> &ovl->cmdq_reg, ovl->regs,
> -			      DISP_REG_OVL_PITCH(idx));
> +	mtk_ddp_write_relaxed(cmdq_pkt, overlay_pitch.split_pitch.lsb |
> ignore_pixel_alpha,
> +			      &ovl->cmdq_reg, ovl->regs,
> DISP_REG_OVL_PITCH(idx));
>  	mtk_ddp_write_relaxed(cmdq_pkt, src_size, &ovl->cmdq_reg, ovl-
> >regs,
>  			      DISP_REG_OVL_SRC_SIZE(idx));
>  	mtk_ddp_write_relaxed(cmdq_pkt, offset, &ovl->cmdq_reg, ovl-
> >regs,