ICL introduces a new gamma correction mode in display engine, called
multi-segmented-gamma mode. This mode allows users to program the
darker region of the gamma curve with sueprfine precision. An
example use case for this is HDR curves (like PQ ST-2084).
If we plot a gamma correction curve from value range between 0.0 to 1.0,
ICL's multi-segment has 3 different sections:
- superfine segment: 9 values, ranges between 0 - 1/(128 * 256)
- fine segment: 257 values, ranges between 0 - 1/(128)
- corase segment: 257 values, ranges between 0 - 1
This patch:
- Changes gamma LUTs size for ICL/GEN11 to 262144 entries (8 * 128 * 256),
so that userspace can program with highest precision supported.
- Changes default gamma mode (non-legacy) to multi-segmented-gamma mode.
- Adds functions to program/detect multi-segment gamma.
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Suggested-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
Signed-off-by: Shashank Sharma <shashank.sha...@intel.com>
Signed-off-by: Uma Shankar <uma.shan...@intel.com>
---
drivers/gpu/drm/i915/i915_pci.c | 3 +-
drivers/gpu/drm/i915/intel_color.c | 155 ++++++++++++++++++++++++++++-
2 files changed, 156 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index ffa2ee70a03d..83698951760b 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -749,7 +749,8 @@ static const struct intel_device_info intel_cannonlake_info
= {
GEN(11), \
.ddb_size = 2048, \
.has_logical_ring_elsq = 1, \
- .color = { .degamma_lut_size = 33, .gamma_lut_size = 1024 }
+ .color = { .degamma_lut_size = 33, .gamma_lut_size = 262144 }
+
static const struct intel_device_info intel_icelake_11_info = {
GEN11_FEATURES,
diff --git a/drivers/gpu/drm/i915/intel_color.c
b/drivers/gpu/drm/i915/intel_color.c
index ca341a9e47e6..d1fb79a5d764 100644
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -41,6 +41,7 @@
#define CTM_COEFF_ABS(coeff) ((coeff) & (CTM_COEFF_SIGN - 1))
#define LEGACY_LUT_LENGTH 256
+#define ICL_MULTISEG_LUT_LENGTH (256 * 128 * 8)
/*
* Extract the CSC coefficient from a CTM coefficient (in U32.32 fixed point
* format). This macro takes the coefficient we want transformed and the
@@ -58,6 +59,12 @@
#define ILK_CSC_POSTOFF_LIMITED_RANGE (16 * (1 << 12) / 255)
+enum icl_ms_gamma_segments {
+ ICL_MS_GAMMA_SEG_SUPERFINE,
+ ICL_MS_GAMMA_SEG_FINE,
+ ICL_MS_GAMMA_SEG_COARSE,
+};
+
static const u16 ilk_csc_off_zero[3] = {};
static const u16 ilk_csc_coeff_identity[9] = {
@@ -767,6 +774,149 @@ static void glk_load_luts(const struct intel_crtc_state
*crtc_state)
}
}
+/* ilk+ "12.4" interpolated format (high 10 bits) */
+static u32 ilk_lut_12p4_ldw(const struct drm_color_lut *color)
+{
+ return (color->red >> 6) << 20 | (color->green >> 6) << 10 |
+ (color->blue >> 6);
+}
+
+/* ilk+ "12.4" interpolated format (low 6 bits) */
+static u32 ilk_lut_12p4_udw(const struct drm_color_lut *color)
+{
+ return (color->red & 0x3f) << 24 | (color->green & 0x3f) << 14 |
+ (color->blue & 0x3f);
+}
+
+static void
+icl_program_gamma_gcmax(const struct intel_crtc_state *crtc_state)
+{
+ struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
+ struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+ enum pipe pipe = crtc->pipe;
+
+ /*
+ * Program the max register to clamp values > 1.0.
+ * ToDo: Extend the ABI to be able to program values
+ * from 1.0
+ */
+ I915_WRITE(PREC_PAL_GC_MAX(pipe, 0), (1 << 16));
+ I915_WRITE(PREC_PAL_GC_MAX(pipe, 1), (1 << 16));
+ I915_WRITE(PREC_PAL_GC_MAX(pipe, 2), (1 << 16));
+
+ /*
+ * Program the max register to clamp values > 1.0.
+ * ToDo: Extend the ABI to be able to program values
+ * from 1.0 to 3.0
+ */
+ I915_WRITE(PREC_PAL_EXT_GC_MAX(pipe, 0), (1 << 16));
+ I915_WRITE(PREC_PAL_EXT_GC_MAX(pipe, 1), (1 << 16));
+ I915_WRITE(PREC_PAL_EXT_GC_MAX(pipe, 2), (1 << 16));
+
+ /*
+ * Program the gc max 2 register to clamp values > 1.0.
+ * ToDo: Extend the ABI to be able to program values
+ * from 3.0 to 7.0
+ */
+ I915_WRITE(PREC_PAL_EXT2_GC_MAX(pipe, 0), (1 << 16));
+ I915_WRITE(PREC_PAL_EXT2_GC_MAX(pipe, 1), (1 << 16));
+ I915_WRITE(PREC_PAL_EXT2_GC_MAX(pipe, 2), (1 << 16));
+}
+
+static void
+icl_program_gamma_multi_segment(const struct intel_crtc_state *crtc_state,
+ const struct drm_property_blob *blob,
+ enum icl_ms_gamma_segments segment)
+{
+ struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
+ struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+ const struct drm_color_lut *lut = blob->data;
+ enum pipe pipe = crtc->pipe;
+ u32 i, word, seg_size, seg_step, seg_start = 0;
+ i915_reg_t index_reg, data_reg;
+
+ if (!lut || (drm_color_lut_size(blob) < ICL_MULTISEG_LUT_LENGTH)) {
+ DRM_DEBUG_KMS("Not programming gamma segment, invalid input\n");
+ return;
+ }
+
+ /*
+ * Every entry in the multi-segment LUT is corresponding to a superfine
+ * segment step which is 1/(8*128*256).
+ *
+ * Superfine segment has 9 entries, corresponding to values
+ * 0, 1/(8 * 128 * 256), 2/(8 * 128 * 256) .... 8/(8 * 128 * 256).
+ *
+ * Fine segment's step is 1/(128 * 256) ie 1/(128 * 256), 2/(128*256)
+ * ... 256/(128*256). So in order to program fine segment of LUT we
+ * need to pick every 8'th entry in LUT, and program 256 indexes.
+ * Fine segment's index 0 is programmed in HW, and it starts from
+ * index 1.
+ *
+ * Coarse segment's starts from index 0 and it's step is 1/256 ie 0,
+ * 1/256, 2/256 ...256/256. As per the description of each entry in LUT
+ * above, we need to pick every 8 * 128 = 1024th entry in LUT, and
+ * program 256 of those.
+ */
+
+ switch (segment) {
+ case ICL_MS_GAMMA_SEG_SUPERFINE:
+ seg_size = 9;
+ seg_step = 1;
+ index_reg = PREC_PAL_MULTI_SEG_INDEX(pipe);
+ data_reg = PREC_PAL_MULTI_SEG_DATA(pipe);
+ break;
+
+ case ICL_MS_GAMMA_SEG_FINE:
+ seg_start = 1;
+ seg_size = 256;
+ seg_step = 8;
+ index_reg = PREC_PAL_INDEX(pipe);
+ data_reg = PREC_PAL_DATA(pipe);
+ break;
+
+ case ICL_MS_GAMMA_SEG_COARSE:
+ seg_size = 256;
+ seg_step = 1024;
+ index_reg = PREC_PAL_INDEX(pipe);
+ data_reg = PREC_PAL_DATA(pipe);
+ break;
+
+ default:
+ DRM_ERROR("Invalid gamma segment %d to program\n", segment);
+ return;
+ }
+
+ I915_WRITE(index_reg, PAL_PREC_AUTO_INCREMENT);
+
+ for (i = seg_start; i < seg_size; i++) {
+ /* Even Index */
+ word = ilk_lut_12p4_udw(&lut[i * seg_step]);
+ I915_WRITE(data_reg, word);
+
+ /* Odd index */
+ word = ilk_lut_12p4_ldw(&lut[i * seg_step]);
+ I915_WRITE(data_reg, word);
+ }
+}
+
+static void
+icl_load_gamma_multi_seg_lut(const struct intel_crtc_state *crtc_state)
+{
+ const struct drm_property_blob *lut_blob = crtc_state->base.gamma_lut;
+
+ if (!lut_blob)
+ return;
+
+ icl_program_gamma_multi_segment(crtc_state, lut_blob,
+ ICL_MS_GAMMA_SEG_SUPERFINE);
+ icl_program_gamma_multi_segment(crtc_state, lut_blob,
+ ICL_MS_GAMMA_SEG_FINE);
+ icl_program_gamma_multi_segment(crtc_state, lut_blob,
+ ICL_MS_GAMMA_SEG_COARSE);
+ icl_program_gamma_gcmax(crtc_state);
+}
+
static void icl_load_luts(const struct intel_crtc_state *crtc_state)
{
const struct drm_property_blob *gamma_lut = crtc_state->base.gamma_lut;
@@ -776,6 +926,9 @@ static void icl_load_luts(const struct intel_crtc_state
*crtc_state)
glk_load_degamma_lut(crtc_state);
if ((crtc_state->gamma_mode & GAMMA_MODE_MODE_MASK) ==
+ GAMMA_MODE_MODE_12BIT_MULTI_SEGMENTED) {
+ icl_load_gamma_multi_seg_lut(crtc_state);
+ } else if ((crtc_state->gamma_mode & GAMMA_MODE_MODE_MASK) ==
GAMMA_MODE_MODE_8BIT) {
i9xx_load_luts(crtc_state);
} else {
@@ -1187,7 +1340,7 @@ static u32 icl_gamma_mode(const struct intel_crtc_state
*crtc_state)
crtc_state_is_legacy_gamma(crtc_state))
gamma_mode |= GAMMA_MODE_MODE_8BIT;
else
- gamma_mode |= GAMMA_MODE_MODE_10BIT;
+ gamma_mode |= GAMMA_MODE_MODE_12BIT_MULTI_SEGMENTED;
return gamma_mode;
}
--
2.17.1
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