[PATCH 0/2] drm/msm/dpu: use full scale alpha in generic code

[PATCH 0/2] drm/msm/dpu: use full scale alpha in generic code

[Dmitry Baryshkov]

Both _dpu_crtc_setup_blend_cfg() and setup_blend_config_alpha()
callbacks embed knowledge about platform's alpha range (8-bit or
10-bit). Make _dpu_crtc_setup_blend_cfg() use full 16-bit values for
alpha and reduce alpha only in DPU-specific callbacks.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
Dmitry Baryshkov (2):
      drm/msm/dpu: simplify bg_alpha selection
      drm/msm/dpu: use full scale alpha in _dpu_crtc_setup_blend_cfg()

 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c  | 18 +++++++-----------
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c | 10 ++++++----
 2 files changed, 13 insertions(+), 15 deletions(-)
---
base-commit: a933d3dc1968fcfb0ab72879ec304b1971ed1b9a
change-id: 20250814-dpu-rework-alpha-060ff6bf5185

Best regards,
-- 
With best wishes
Dmitry

[PATCH 1/2] drm/msm/dpu: simplify bg_alpha selection

[Dmitry Baryshkov]

In order to be more obvious in fg_alpha / bg_alpha handling during the
blending programming drop the default setting for background alpha value
and set it explicitly in all cases.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index d4b545448d74657aafc96e9042c7756654b4f0e7..651159e8731194d75b52c05158bfd1c9bad8b10c 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -335,13 +335,13 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 		max_alpha = 0x3ff;
 		fg_alpha = pstate->base.alpha >> 6;
 	}
-	bg_alpha = max_alpha - fg_alpha;
 
 	/* default to opaque blending */
 	if (pstate->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
 	    !format->alpha_enable) {
 		blend_op = DPU_BLEND_FG_ALPHA_FG_CONST |
 			DPU_BLEND_BG_ALPHA_BG_CONST;
+		bg_alpha = max_alpha - fg_alpha;
 	} else if (pstate->base.pixel_blend_mode == DRM_MODE_BLEND_PREMULTI) {
 		blend_op = DPU_BLEND_FG_ALPHA_FG_CONST |
 			DPU_BLEND_BG_ALPHA_FG_PIXEL;
@@ -350,6 +350,7 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 			blend_op |= DPU_BLEND_BG_MOD_ALPHA |
 				    DPU_BLEND_BG_INV_MOD_ALPHA;
 		} else {
+			bg_alpha = 0;
 			blend_op |= DPU_BLEND_BG_INV_ALPHA;
 		}
 	} else {
@@ -363,6 +364,7 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 				    DPU_BLEND_BG_MOD_ALPHA |
 				    DPU_BLEND_BG_INV_MOD_ALPHA;
 		} else {
+			bg_alpha = 0;
 			blend_op |= DPU_BLEND_BG_INV_ALPHA;
 		}
 	}

-- 
2.47.2

[PATCH 2/2] drm/msm/dpu: use full scale alpha in _dpu_crtc_setup_blend_cfg()

[Dmitry Baryshkov]

Both _dpu_crtc_setup_blend_cfg() and setup_blend_config_alpha()
callbacks embed knowledge about platform's alpha range (8-bit or
10-bit). Make _dpu_crtc_setup_blend_cfg() use full 16-bit values for
alpha and reduce alpha only in DPU-specific callbacks.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c  | 16 +++++-----------
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c | 10 ++++++----
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 651159e8731194d75b52c05158bfd1c9bad8b10c..a280c136104added1dbb2b432f15680bc1d5bd36 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -326,26 +326,20 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 {
 	struct dpu_hw_mixer *lm = mixer->hw_lm;
 	u32 blend_op;
-	u32 fg_alpha, bg_alpha, max_alpha;
+	u32 fg_alpha, bg_alpha;
 
-	if (mdss_ver->core_major_ver < 12) {
-		max_alpha = 0xff;
-		fg_alpha = pstate->base.alpha >> 8;
-	} else {
-		max_alpha = 0x3ff;
-		fg_alpha = pstate->base.alpha >> 6;
-	}
+	fg_alpha = pstate->base.alpha;
 
 	/* default to opaque blending */
 	if (pstate->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
 	    !format->alpha_enable) {
 		blend_op = DPU_BLEND_FG_ALPHA_FG_CONST |
 			DPU_BLEND_BG_ALPHA_BG_CONST;
-		bg_alpha = max_alpha - fg_alpha;
+		bg_alpha = DRM_BLEND_ALPHA_OPAQUE - fg_alpha;
 	} else if (pstate->base.pixel_blend_mode == DRM_MODE_BLEND_PREMULTI) {
 		blend_op = DPU_BLEND_FG_ALPHA_FG_CONST |
 			DPU_BLEND_BG_ALPHA_FG_PIXEL;
-		if (fg_alpha != max_alpha) {
+		if (fg_alpha != DRM_BLEND_ALPHA_OPAQUE) {
 			bg_alpha = fg_alpha;
 			blend_op |= DPU_BLEND_BG_MOD_ALPHA |
 				    DPU_BLEND_BG_INV_MOD_ALPHA;
@@ -357,7 +351,7 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 		/* coverage blending */
 		blend_op = DPU_BLEND_FG_ALPHA_FG_PIXEL |
 			DPU_BLEND_BG_ALPHA_FG_PIXEL;
-		if (fg_alpha != max_alpha) {
+		if (fg_alpha != DRM_BLEND_ALPHA_OPAQUE) {
 			bg_alpha = fg_alpha;
 			blend_op |= DPU_BLEND_FG_MOD_ALPHA |
 				    DPU_BLEND_FG_INV_MOD_ALPHA |
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c
index e8a76d5192c230fd64d748634ca8574a59aac02c..fb8c94fdb829be6f89bfcc6c5a83fdbd27778bf2 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c
@@ -139,7 +139,8 @@ static void dpu_hw_lm_setup_blend_config_combined_alpha(struct dpu_hw_mixer *ctx
 	if (WARN_ON(stage_off < 0))
 		return;
 
-	const_alpha = (bg_alpha & 0xFF) | ((fg_alpha & 0xFF) << 16);
+	const_alpha = ((bg_alpha >> 8) & 0xff) |
+		(((fg_alpha >> 8) & 0xff) << 16);
 	DPU_REG_WRITE(c, LM_BLEND0_CONST_ALPHA + stage_off, const_alpha);
 	DPU_REG_WRITE(c, LM_BLEND0_OP + stage_off, blend_op);
 }
@@ -160,7 +161,8 @@ dpu_hw_lm_setup_blend_config_combined_alpha_v12(struct dpu_hw_mixer *ctx,
 	if (WARN_ON(stage_off < 0))
 		return;
 
-	const_alpha = (bg_alpha & 0x3ff) | ((fg_alpha & 0x3ff) << 16);
+	const_alpha = ((bg_alpha >> 6) & 0x3ff) |
+		(((fg_alpha >> 6) & 0x3ff) << 16);
 	DPU_REG_WRITE(c, LM_BLEND0_CONST_ALPHA_V12 + stage_off, const_alpha);
 	DPU_REG_WRITE(c, LM_BLEND0_OP + stage_off, blend_op);
 }
@@ -178,8 +180,8 @@ static void dpu_hw_lm_setup_blend_config(struct dpu_hw_mixer *ctx,
 	if (WARN_ON(stage_off < 0))
 		return;
 
-	DPU_REG_WRITE(c, LM_BLEND0_FG_ALPHA + stage_off, fg_alpha);
-	DPU_REG_WRITE(c, LM_BLEND0_BG_ALPHA + stage_off, bg_alpha);
+	DPU_REG_WRITE(c, LM_BLEND0_FG_ALPHA + stage_off, fg_alpha >> 8);
+	DPU_REG_WRITE(c, LM_BLEND0_BG_ALPHA + stage_off, bg_alpha >> 8);
 	DPU_REG_WRITE(c, LM_BLEND0_OP + stage_off, blend_op);
 }
 

-- 
2.47.2