[Intel-gfx] [PATCH 11/20] drm/i915: Do degamma+gamma readout in bdw+ split gamma mode

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Read out both gamma and degamma when usng the split gamma mode
on bdw+. We can't use the auto increment mode to iterate the
LUTs since we want to read out less entries than what we stuff
into the software LUT.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_color.c | 52 +++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
index 5742ac1af862..f34257922e4d 100644
--- a/drivers/gpu/drm/i915/display/intel_color.c
+++ b/drivers/gpu/drm/i915/display/intel_color.c
@@ -1959,6 +1959,46 @@ static void ilk_read_luts(struct intel_crtc_state *crtc_state)
 		crtc_state->hw.gamma_lut = ilk_read_lut_10(crtc);
 }
 
+/*
+ * IVB/HSW Bspec / PAL_PREC_INDEX:
+ * "Restriction : Index auto increment mode is not
+ *  supported and must not be enabled."
+ */
+static struct drm_property_blob *ivb_read_lut_10(struct intel_crtc *crtc,
+						 u32 prec_index)
+{
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	int i, hw_lut_size = ivb_lut_10_size(prec_index);
+	int lut_size = INTEL_INFO(dev_priv)->color.gamma_lut_size;
+	enum pipe pipe = crtc->pipe;
+	struct drm_property_blob *blob;
+	struct drm_color_lut *lut;
+
+	blob = drm_property_create_blob(&dev_priv->drm,
+					sizeof(struct drm_color_lut) * lut_size,
+					NULL);
+	if (IS_ERR(blob))
+		return NULL;
+
+	lut = blob->data;
+
+	for (i = 0; i < lut_size; i++) {
+		/* We discard half the user entries in split gamma mode */
+		int index = DIV_ROUND_UP(i * (hw_lut_size - 1), lut_size - 1);
+		u32 val;
+
+		intel_de_write(dev_priv, PREC_PAL_INDEX(pipe),
+			       prec_index + index);
+		val = intel_de_read(dev_priv, PREC_PAL_DATA(pipe));
+
+		ilk_lut_10_pack(&lut[i], val);
+	}
+
+	intel_de_write(dev_priv, PREC_PAL_INDEX(pipe), 0);
+
+	return blob;
+}
+
 /* On BDW+ the index auto increment mode actually works */
 static struct drm_property_blob *bdw_read_lut_10(struct intel_crtc *crtc,
 						 u32 prec_index)
@@ -2006,7 +2046,17 @@ static void bdw_read_luts(struct intel_crtc_state *crtc_state)
 		*blob = ilk_read_lut_8(crtc);
 		break;
 	case GAMMA_MODE_MODE_SPLIT:
-		/* FIXME */
+		/*
+		 * Can't use bdw_read_lut_10() with its auto-increment
+		 * mode here since we want to generate 1024 entry
+		 * software LUTs from the 512 entry hardware LUTs.
+		 */
+		crtc_state->hw.degamma_lut =
+			ivb_read_lut_10(crtc, PAL_PREC_SPLIT_MODE |
+					PAL_PREC_INDEX_VALUE(0));
+		crtc_state->hw.gamma_lut =
+			ivb_read_lut_10(crtc, PAL_PREC_SPLIT_MODE |
+					PAL_PREC_INDEX_VALUE(512));
 		break;
 	case GAMMA_MODE_MODE_10BIT:
 		*blob = bdw_read_lut_10(crtc, PAL_PREC_INDEX_VALUE(0));
-- 
2.26.2