* [PATCH 1/2] drm/msm/dpu: simplify bg_alpha selection
2025-08-14 9:03 [PATCH 0/2] drm/msm/dpu: use full scale alpha in generic code Dmitry Baryshkov
@ 2025-08-14 9:03 ` Dmitry Baryshkov
2025-08-14 9:03 ` [PATCH 2/2] drm/msm/dpu: use full scale alpha in _dpu_crtc_setup_blend_cfg() Dmitry Baryshkov
1 sibling, 0 replies; 3+ messages in thread
From: Dmitry Baryshkov @ 2025-08-14 9:03 UTC (permalink / raw)
To: Rob Clark, Dmitry Baryshkov, Abhinav Kumar, Jessica Zhang,
Sean Paul, Marijn Suijten, David Airlie, Simona Vetter
Cc: linux-arm-msm, dri-devel, freedreno, linux-kernel
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
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] drm/msm/dpu: use full scale alpha in _dpu_crtc_setup_blend_cfg()
2025-08-14 9:03 [PATCH 0/2] drm/msm/dpu: use full scale alpha in generic code Dmitry Baryshkov
2025-08-14 9:03 ` [PATCH 1/2] drm/msm/dpu: simplify bg_alpha selection Dmitry Baryshkov
@ 2025-08-14 9:03 ` Dmitry Baryshkov
1 sibling, 0 replies; 3+ messages in thread
From: Dmitry Baryshkov @ 2025-08-14 9:03 UTC (permalink / raw)
To: Rob Clark, Dmitry Baryshkov, Abhinav Kumar, Jessica Zhang,
Sean Paul, Marijn Suijten, David Airlie, Simona Vetter
Cc: linux-arm-msm, dri-devel, freedreno, linux-kernel
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
^ permalink raw reply related [flat|nested] 3+ messages in thread