Re: [PATCH v9 16/21] drm/mediatek: Support "Pre-multiplied" blending in OVL
From: CK Hu (胡俊光)
Date: Fri Jun 14 2024 - 01:43:22 EST
On Fri, 2024-06-14 at 10:46 +0800, Shawn Sung wrote:
> From: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
>
> Support "Pre-multiplied" alpha blending mode on in OVL.
> Before this patch, only the "coverage" mode is supported.
>
> Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 42 ++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index 6567806cf4e2..47d0b039a616 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -52,8 +52,12 @@
> #define GMC_THRESHOLD_HIGH ((1 << GMC_THRESHOLD_BITS) / 4)
> #define GMC_THRESHOLD_LOW ((1 << GMC_THRESHOLD_BITS) / 8)
>
> +#define OVL_CON_CLRFMT_MAN BIT(23)
> #define OVL_CON_BYTE_SWAP BIT(24)
> -#define OVL_CON_MTX_YUV_TO_RGB (6 << 16)
> +
> +/* OVL_CON_RGB_SWAP works only if OVL_CON_CLRFMT_MAN is enabled */
> +#define OVL_CON_RGB_SWAP BIT(25)
> +
> #define OVL_CON_CLRFMT_RGB (1 << 12)
> #define OVL_CON_CLRFMT_ARGB8888 (2 << 12)
> #define OVL_CON_CLRFMT_RGBA8888 (3 << 12)
> @@ -61,6 +65,11 @@
> #define OVL_CON_CLRFMT_BGRA8888 (OVL_CON_CLRFMT_ARGB8888 | OVL_CON_BYTE_SWAP)
> #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_PARGB8888 ((3 << 12) | OVL_CON_CLRFMT_MAN)
#define OVL_CON_CLRFMT_PARGB8888 (OVL_CON_CLRFMT_RGBA8888 | OVL_CON_CLRFMT_MAN)
But I'm confused with the naming.
> +#define OVL_CON_CLRFMT_PABGR8888 (OVL_CON_CLRFMT_PARGB8888 | OVL_CON_RGB_SWAP)
#define OVL_CON_CLRFMT_PABGR8888 (OVL_CON_CLRFMT_ABGR8888 | OVL_CON_CLRFMT_MAN)
> +#define OVL_CON_CLRFMT_PBGRA8888 (OVL_CON_CLRFMT_PARGB8888 | OVL_CON_BYTE_SWAP)
#define OVL_CON_CLRFMT_PBGRA8888 (OVL_CON_CLRFMT_BGRA8888 | OVL_CON_CLRFMT_MAN)
> +#define OVL_CON_CLRFMT_PRGBA8888 (OVL_CON_CLRFMT_PABGR8888 | OVL_CON_BYTE_SWAP)
> #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 ? \
> @@ -74,6 +83,8 @@
> #define OVL_CON_VIRT_FLIP BIT(9)
> #define OVL_CON_HORZ_FLIP BIT(10)
>
> +#define OVL_COLOR_ALPHA GENMASK(31, 24)
> +
> static inline bool is_10bit_rgb(u32 fmt)
> {
> switch (fmt) {
> @@ -298,7 +309,13 @@ 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 must be opaque black (ARGB),
> + * otherwise the alpha blending will have no effect
> + */
> + mtk_ddp_write_relaxed(cmdq_pkt, OVL_COLOR_ALPHA, &ovl->cmdq_reg,
> + ovl->regs, DISP_REG_OVL_ROI_BGCLR);
The coverage mode formula is:
dst.RGB = src.RGB * src.A + dst.RGB * (1 - src.A)
The pre-multiplied mode formula is:
dst.RGB = src.RGB + dst.RGB * (1 - src.A)
Both formula has no destination alpha (I think background color is last destination),
why coverage mode work fine but pre-multiplied mode has something wrong?
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);
> @@ -374,7 +391,8 @@ 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.
> @@ -395,22 +413,30 @@ static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt)
> case DRM_FORMAT_RGBA8888:
> case DRM_FORMAT_RGBX1010102:
> case DRM_FORMAT_RGBA1010102:
> - return OVL_CON_CLRFMT_RGBA8888;
> + return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> + OVL_CON_CLRFMT_RGBA8888 :
> + OVL_CON_CLRFMT_PRGBA8888;
> case DRM_FORMAT_BGRX8888:
> case DRM_FORMAT_BGRA8888:
> case DRM_FORMAT_BGRX1010102:
> case DRM_FORMAT_BGRA1010102:
> - return OVL_CON_CLRFMT_BGRA8888;
> + return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> + OVL_CON_CLRFMT_BGRA8888 :
> + OVL_CON_CLRFMT_PBGRA8888;
> case DRM_FORMAT_XRGB8888:
> case DRM_FORMAT_ARGB8888:
> case DRM_FORMAT_XRGB2101010:
> case DRM_FORMAT_ARGB2101010:
> - return OVL_CON_CLRFMT_ARGB8888;
> + return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> + OVL_CON_CLRFMT_ARGB8888 :
> + OVL_CON_CLRFMT_PARGB8888;
> case DRM_FORMAT_XBGR8888:
> case DRM_FORMAT_ABGR8888:
> case DRM_FORMAT_XBGR2101010:
> case DRM_FORMAT_ABGR2101010:
> - return OVL_CON_CLRFMT_ABGR8888;
> + return blend_mode == DRM_MODE_BLEND_COVERAGE ?
> + OVL_CON_CLRFMT_ABGR8888 :
> + OVL_CON_CLRFMT_PABGR8888;
> case DRM_FORMAT_UYVY:
> return OVL_CON_CLRFMT_UYVY | OVL_CON_MTX_YUV_TO_RGB;
> case DRM_FORMAT_YUYV:
> @@ -450,7 +476,7 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
> return;
> }
>
> - con = ovl_fmt_convert(ovl, fmt);
> + con = ovl_fmt_convert(ovl, fmt, blend_mode);
> if (state->base.fb) {
> con |= OVL_CON_AEN;
> con |= state->base.alpha & OVL_CON_ALPHA;