[Intel-gfx] [PATCH 12/13] drm/i915: Turn off pipe CSC when it's not needed

[Ville Syrjala]

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

As with pipe gamma we can avoid the potential precision loss from
the pipe csc unit when there is no need to use it. And again
we need the same logic for updating the planes.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_color.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index a8b7428a64bf..789b04bb51d2 100644
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -659,7 +659,8 @@ intel_color_add_affected_planes(struct intel_crtc_state *new_crtc_state)
 		intel_atomic_get_old_crtc_state(state, crtc);
 	struct intel_plane *plane;
 
-	if (new_crtc_state->gamma_enable == old_crtc_state->gamma_enable)
+	if (new_crtc_state->gamma_enable == old_crtc_state->gamma_enable &&
+	    new_crtc_state->csc_enable == old_crtc_state->csc_enable)
 		return 0;
 
 	for_each_intel_plane_on_crtc(&dev_priv->drm, crtc, plane) {
@@ -684,6 +685,7 @@ int intel_color_check(struct intel_crtc_state *crtc_state)
 	const struct drm_property_blob *gamma_lut = crtc_state->base.gamma_lut;
 	const struct drm_property_blob *degamma_lut = crtc_state->base.degamma_lut;
 	size_t gamma_length, degamma_length;
+	bool limited_color_range = false;
 	int ret;
 
 	degamma_length = INTEL_INFO(dev_priv)->color.degamma_lut_size;
@@ -693,7 +695,11 @@ int intel_color_check(struct intel_crtc_state *crtc_state)
 
 	if (INTEL_GEN(dev_priv) >= 9 ||
 	    IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv))
-		crtc_state->csc_enable = true;
+		limited_color_range = crtc_state->limited_color_range;
+
+	crtc_state->csc_enable =
+		crtc_state->output_format != INTEL_OUTPUT_FORMAT_RGB ||
+		crtc_state->base.ctm || limited_color_range;
 
 	ret = intel_color_add_affected_planes(crtc_state);
 	if (ret)
-- 
2.19.2