Fixes broken grayscale ramps on many HDMI monitors, where large areas
at the ends of the ramp would all appear as black or white.
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 31 +++++++++++++++++++++++++++++--
drivers/gpu/drm/vc4/vc4_regs.h | 9 ++++++++-
2 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 9f85a579da74..1e61931846d3 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -301,6 +301,7 @@ static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
struct drm_display_mode *unadjusted_mode,
struct drm_display_mode *mode)
{
+ struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
struct drm_device *dev = encoder->dev;
struct vc4_dev *vc4 = to_vc4_dev(dev);
bool debug_dump_regs = false;
@@ -316,6 +317,7 @@ static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
u32 vertb = (VC4_SET_FIELD(0, VC4_HDMI_VERTB_VSPO) |
VC4_SET_FIELD(mode->vtotal - mode->vsync_end,
VC4_HDMI_VERTB_VBP));
+ u32 csc_ctl;
if (debug_dump_regs) {
DRM_INFO("HDMI regs before:\n");
@@ -354,9 +356,34 @@ static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
(vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
(hsync_pos ? 0 : VC4_HD_VID_CTL_HSYNC_LOW));
+ csc_ctl = VC4_SET_FIELD(VC4_HD_CSC_CTL_ORDER_BGR,
+ VC4_HD_CSC_CTL_ORDER);
+
+ if (vc4_encoder->hdmi_monitor && drm_match_cea_mode(mode) > 1) {
+ /* CEA VICs other than #1 requre limited range RGB
+ * output. Apply a colorspace conversion to squash
+ * 0-255 down to 16-235. The matrix here is:
+ *
+ * [ 0 0 0.8594 16]
+ * [ 0 0.8594 0 16]
+ * [ 0.8594 0 0 16]
+ * [ 0 0 0 1]
+ */
+ csc_ctl |= VC4_HD_CSC_CTL_ENABLE;
+ csc_ctl |= VC4_HD_CSC_CTL_RGB2YCC;
+ csc_ctl |= VC4_SET_FIELD(VC4_HD_CSC_CTL_MODE_CUSTOM,
+ VC4_HD_CSC_CTL_MODE);
+
+ HD_WRITE(VC4_HD_CSC_12_11, (0x000 << 16) | 0x000);
+ HD_WRITE(VC4_HD_CSC_14_13, (0x100 << 16) | 0x6e0);
+ HD_WRITE(VC4_HD_CSC_22_21, (0x6e0 << 16) | 0x000);
+ HD_WRITE(VC4_HD_CSC_24_23, (0x100 << 16) | 0x000);
+ HD_WRITE(VC4_HD_CSC_32_31, (0x000 << 16) | 0x6e0);
+ HD_WRITE(VC4_HD_CSC_34_33, (0x100 << 16) | 0x000);
+ }
+
/* The RGB order applies even when CSC is disabled. */
- HD_WRITE(VC4_HD_CSC_CTL, VC4_SET_FIELD(VC4_HD_CSC_CTL_ORDER_BGR,
- VC4_HD_CSC_CTL_ORDER));
+ HD_WRITE(VC4_HD_CSC_CTL, csc_ctl);
HDMI_WRITE(VC4_HDMI_FIFO_CTL, VC4_HDMI_FIFO_CTL_MASTER_SLAVE_N);
diff --git a/drivers/gpu/drm/vc4/vc4_regs.h b/drivers/gpu/drm/vc4/vc4_regs.h
index 160942a9180e..9ecd6ff3d493 100644
--- a/drivers/gpu/drm/vc4/vc4_regs.h
+++ b/drivers/gpu/drm/vc4/vc4_regs.h
@@ -528,10 +528,17 @@
# define VC4_HD_CSC_CTL_MODE_SHIFT 2
# define VC4_HD_CSC_CTL_MODE_RGB_TO_SD_YPRPB 0
# define VC4_HD_CSC_CTL_MODE_RGB_TO_HD_YPRPB 1
-# define VC4_HD_CSC_CTL_MODE_CUSTOM 2
+# define VC4_HD_CSC_CTL_MODE_CUSTOM 3
# define VC4_HD_CSC_CTL_RGB2YCC BIT(1)
# define VC4_HD_CSC_CTL_ENABLE BIT(0)
+#define VC4_HD_CSC_12_11 0x044
+#define VC4_HD_CSC_14_13 0x048
+#define VC4_HD_CSC_22_21 0x04c
+#define VC4_HD_CSC_24_23 0x050
+#define VC4_HD_CSC_32_31 0x054
+#define VC4_HD_CSC_34_33 0x058
+
#define VC4_HD_FRAME_COUNT 0x068
/* HVS display list information. */
--
2.9.3
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