drm/i915: Enable pipe HDR mode on ICL if only HDR planes are used

The pipe has a special HDR mode with higher precision when only
HDR planes are active. Let's use it.

Curiously this fixes the kms_color gamma/degamma tests when
using a HDR plane, which is always the case unless one hacks
the test to use an SDR plane. If one does hack the test to use
an SDR plane it does pass already.

I have no actual explanation how the output after the gamma
LUT can be different between the two modes. The way the tests
are written should mean that the output should be identical
between the solid color vs. the gradient. But clearly that
somehow doesn't hold true for the HDR planes in non-HDR pipe
mode. Anyways, as long as we stick to one type of plane the
test should produce sensible results now.

v2: s/HDR_MODE/HDR_MODE_PRECISION/ (Shashank)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190412183009.8237-2-ville.syrjala@linux.intel.comReviewed-by: Uma Shankar <uma.shankar@intel.com>
Tested-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -5770,6 +5770,7 @@ enum {
 #define _PIPE_MISC_B			0x71030
 #define   PIPEMISC_YUV420_ENABLE	(1 << 27)
 #define   PIPEMISC_YUV420_MODE_FULL_BLEND (1 << 26)
+#define   PIPEMISC_HDR_MODE_PRECISION	(1 << 23) /* icl+ */
 #define   PIPEMISC_OUTPUT_COLORSPACE_YUV  (1 << 11)
 #define   PIPEMISC_DITHER_BPC_MASK	(7 << 5)
 #define   PIPEMISC_DITHER_8_BPC		(0 << 5)

drivers/gpu/drm/i915/intel_display.c

@@ -4099,6 +4099,9 @@ static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_sta
 			ironlake_pfit_disable(old_crtc_state);
 	}
 
+	if (INTEL_GEN(dev_priv) >= 9 || IS_BROADWELL(dev_priv))
+		bdw_set_pipemisc(new_crtc_state);
+
 	if (INTEL_GEN(dev_priv) >= 11)
 		icl_set_pipe_chicken(crtc);
 }
@@ -8926,6 +8929,10 @@ static void bdw_set_pipemisc(const struct intel_crtc_state *crtc_state)
 		val |= PIPEMISC_YUV420_ENABLE |
 			PIPEMISC_YUV420_MODE_FULL_BLEND;
 
+	if (INTEL_GEN(dev_priv) >= 11 &&
+	    (crtc_state->active_planes & ~icl_hdr_plane_mask()) == 0)
+		val |= PIPEMISC_HDR_MODE_PRECISION;
+
 	I915_WRITE(PIPEMISC(crtc->pipe), val);
 }
 

drivers/gpu/drm/i915/intel_sprite.h

@@ -43,13 +43,17 @@ static inline bool icl_is_nv12_y_plane(enum plane_id id)
 	return false;
 }
 
+static inline u8 icl_hdr_plane_mask(void)
+{
+	return BIT(PLANE_PRIMARY) |
+		BIT(PLANE_SPRITE0) | BIT(PLANE_SPRITE1);
+}
+
 static inline bool icl_is_hdr_plane(struct drm_i915_private *dev_priv,
 				    enum plane_id plane_id)
 {
-	if (INTEL_GEN(dev_priv) < 11)
-		return false;
-
-	return plane_id < PLANE_SPRITE2;
+	return INTEL_GEN(dev_priv) >= 11 &&
+		icl_hdr_plane_mask() & BIT(plane_id);
 }
 
 #endif /* __INTEL_SPRITE_H__ */