Re: [PATCH v9 16/21] drm/mediatek: Support "Pre-multiplied" blending in OVL

["Jason-JH Lin (林睿祥)" <Jason-JH.Lin@mediatek.com>]

Hi CK,

On Wed, 2024-06-19 at 03:17 +0000, CK Hu (胡俊光) wrote:
> Hi, Jason:
> 
> On Tue, 2024-06-18 at 17:00 +0000, Jason-JH Lin (林睿祥) wrote:
> > Hi CK,
> > 
> > On Fri, 2024-06-14 at 05:42 +0000, CK Hu (胡俊光) wrote:
> > > On Fri, 2024-06-14 at 10:46 +0800, Shawn Sung wrote:
> > > > From: Hsiao Chien Sung <shawn.sung@mediatek.com>
> > > > 
> > > > 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@mediatek.com>
> > > > ---
> > > >  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_ARGB888
> > > > 8 |
> > > > 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.
> > > 
> > 
> > We found that original naming is not correct, so we fix it with the
> > patch:
> > 
> > 
https://patchwork.kernel.org/project/linux-mediatek/patch/20240616-mediatek-drm-next-v1-11-7e8f9cf785d8@mediatek.com/
> > 
> > PARGB8888 is not ARGB8888 + MAN.
> > 
> > If DISP_REG_OVL_CON open the MAN bit, some original color format
> > settings will be changed, for example:
> > 
> > When MAN = 0:
> > RGB565 = 0000 in bit[15:12]
> > RGB888 = 0001 in bit[15:12]
> > ARGB8888 = 0010 in bit[15:12]
> > RGBA8888 = 0011 in bit[15:12]
> > UYVY = 0100 in bit[15:12]
> > YUYV = 0101 in bit[15:12]
> > 
> > When MAN = 1:
> > RGB888 = 0000 in bit[15:12]
> > RGB565 = 0001 in bit[15:12]
> > BGRA
> > 8888 = 0010 in bit[15:12]
> > PARGB8888 = 0011 in bit[15:12]BGRA4444 = 0100
> > in bit[15:12]
> > BGRA5551 = 0101 in bit[15:12]
> > YUYV = 1000 in bit[15:12]
> > UYVY
> > = 1001 in bit[15:12]
> > YVYU = 1010 in bit[15:12]
> > VYUY = 1011 in bit[15:12]
> 
> I think you could define premultiplied format as:
> 
> #define PRGB888		(0 << 12) | OVL_CON_CLRFMT_MAN
> #define PRGB565		(1 << 12) | OVL_CON_CLRFMT_MAN
> #define PBGRA8888	(2 << 12) | OVL_CON_CLRFMT_MAN
> #define PARGB8888	(3 << 12) | OVL_CON_CLRFMT_MAN
> #define PBGRA4444	(4 << 12) | OVL_CON_CLRFMT_MAN
> #define PBGRA5551	(5 << 12) | OVL_CON_CLRFMT_MAN
> #define PYUYV		(8 << 12) | OVL_CON_CLRFMT_MAN
> #define PVYUY		(9 << 12) | OVL_CON_CLRFMT_MAN
> 

OVL_CON_CLRFMT_MAN = 1 is for extending the color format, not for
enabling the Pre-multipled, so I think we only need to define the new
format PARGB8888  (3 << 12) | OVL_CON_CLRFMT_MAN.

Then we can use RGB_SAP and BYTE_SWAP to change PARGB8888 to other Pre-
Multiplied 8888 color formats.

Keep using the color format that is support with OVL_CON_CLRFMT_MAN = 0
for the previous SoC.

> > 
> > > 
> > > > +#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?
> > > 
> > 
> > alpha of coverage mode formula is:
> > dst.a = dst.a x (0xff - src.a x SCA/0xff)/0xff + src.a x SCA/0xff;
> > 
> > alpha of pre-multiplied mode is:
> > dst.a = round( {{dst.a x [0xff - round((src.a x SCA)/0xff)]} /
> > 0xff} +
> > round((src.a x SCA)/0xff) );
> > 
> > * SCA is constant alpha
> > 
> > If SCA = 0xff, then the formula will be:
> > dst.a = dst.a x (0xff - src.a) + src.a
> > 
> > If dst.a is 0, then dst.a will be src.a
> > If dst.a is 0xff, then dst.a will be 0xff
> 
> I'm confused that dst.a exist in both side of '='. Let me name them
> as dst.a.new and dst.a.old.
> So calculate dst.a.new first, then calculate dst.RGB according to
> dst.a.new not dst.a.old?
> 
> If so, dst.a.new is influenced by SCA either in coverage mode and
> premultiplied mode.
> This is to fix the bug already exist in coverage mode.
> 
Yes, I'll separate this to another patch.

Regards,
Jason-JH Lin

> Regards,
> CK
> 
> > 
> > 
> > Regards,
> > Jason-JH Lin
> > 
> > > 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;