drm/i915: Don't mangle the CTM on pre-HSW

On pre-HSW we have dedicated hardware for the RGB limited range
handling, and so we don't want to compress with the CSC matrix.

Toss in a FIXME about gamma LUT vs. limited range using the CSC.

Cc: Johnson Lin <johnson.lin@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180222214232.6064-4-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index af1e61d..89ab0f7 100644 (file)
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -140,6 +140,14 @@ static void ilk_load_csc_matrix(struct drm_crtc_state *crtc_state)
        int i, pipe = intel_crtc->pipe;
        uint16_t coeffs[9] = { 0, };
        struct intel_crtc_state *intel_crtc_state = to_intel_crtc_state(crtc_state);
+       bool limited_color_range = false;
+
+       /*
+        * FIXME if there's a gamma LUT after the CSC, we should
+        * do the range compression using the gamma LUT instead.
+        */
+       if (INTEL_GEN(dev_priv) >= 8 || IS_HASWELL(dev_priv))
+               limited_color_range = intel_crtc_state->limited_color_range;
 
        if (intel_crtc_state->ycbcr420) {
                ilk_load_ycbcr_conversion_matrix(intel_crtc);
@@ -150,7 +158,7 @@ static void ilk_load_csc_matrix(struct drm_crtc_state *crtc_state)
                const u64 *input;
                u64 temp[9];
 
-               if (intel_crtc_state->limited_color_range)
+               if (limited_color_range)
                        input = ctm_mult_by_limited(temp, ctm->matrix);
                else
                        input = ctm->matrix;
@@ -200,7 +208,7 @@ static void ilk_load_csc_matrix(struct drm_crtc_state *crtc_state)
                 * into consideration.
                 */
                for (i = 0; i < 3; i++) {
-                       if (intel_crtc_state->limited_color_range)
+                       if (limited_color_range)
                                coeffs[i * 3 + i] =
                                        ILK_CSC_COEFF_LIMITED_RANGE;
                        else
@@ -224,7 +232,7 @@ static void ilk_load_csc_matrix(struct drm_crtc_state *crtc_state)
        if (INTEL_GEN(dev_priv) > 6) {
                uint16_t postoff = 0;
 
-               if (intel_crtc_state->limited_color_range)
+               if (limited_color_range)
                        postoff = (16 * (1 << 12) / 255) & 0x1fff;
 
                I915_WRITE(PIPE_CSC_POSTOFF_HI(pipe), postoff);
@@ -235,7 +243,7 @@ static void ilk_load_csc_matrix(struct drm_crtc_state *crtc_state)
        } else {
                uint32_t mode = CSC_MODE_YUV_TO_RGB;
 
-               if (intel_crtc_state->limited_color_range)
+               if (limited_color_range)
                        mode |= CSC_BLACK_SCREEN_OFFSET;
 
                I915_WRITE(PIPE_CSC_MODE(pipe), mode);