drm/i915: Disable sprite gamma on ivb-bdw

We don't currently have any use for the sprite gamma on ivb-bdw.
Let's disable it. We already do that on skl+.

On pre-ivb there is no way to disable the sprite gamma, and it
only affects YCbCr pixel formats, whereas on ivb+ it also
affects RGB formats.
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703200824.5971-3-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/intel_sprite.c

@@ -1013,6 +1013,8 @@ static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
 		return 0;
 	}
 
+	sprctl |= SPRITE_INT_GAMMA_DISABLE;
+
 	if (plane_state->base.color_encoding == DRM_COLOR_YCBCR_BT709)
 		sprctl |= SPRITE_YUV_TO_RGB_CSC_FORMAT_BT709;
 

drivers/gpu/drm/i915/i915_reg.h

@@ -6465,7 +6465,7 @@ enum {
 #define   SPRITE_YUV_ORDER_VYUY		(3 << 16)
 #define   SPRITE_ROTATE_180		(1 << 15)
 #define   SPRITE_TRICKLE_FEED_DISABLE	(1 << 14)
-#define   SPRITE_INT_GAMMA_ENABLE	(1 << 13)
+#define   SPRITE_INT_GAMMA_DISABLE	(1 << 13)
 #define   SPRITE_TILED			(1 << 10)
 #define   SPRITE_DEST_KEY		(1 << 2)
 #define _SPRA_LINOFF		0x70284