drm/i915: Add debugs for the C8 vs. legacy LUT case

Leave a hint in dmesg when we reject a configuration attempting
to use C8 planes without the legacy LUT loaded.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190513133904.20374-3-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index 962db12..4564990 100644 (file)
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -959,8 +959,10 @@ static int check_luts(const struct intel_crtc_state *crtc_state)
                return 0;
 
        /* C8 relies on its palette being stored in the legacy LUT */
-       if (crtc_state->c8_planes)
+       if (crtc_state->c8_planes) {
+               DRM_DEBUG_KMS("C8 pixelformat requires the legacy LUT\n");
                return -EINVAL;
+       }
 
        degamma_length = INTEL_INFO(dev_priv)->color.degamma_lut_size;
        gamma_length = INTEL_INFO(dev_priv)->color.gamma_lut_size;