drm/i915/glk: Refactor handling of PLANE_COLOR_CTL for GLK+

Since GLK, some plane configuration settings have moved to the
PLANE_COLOR_CTL register. Refactor handling of the register to work like
PLANE_CTL. This also allows us to fix the set/read of the plane Alpha
Mode for GLK+.

v2: Adjust ordering of platform checks to be newest->oldest, drop
redundant comment about alpha blending. (Ville)

v3: Move Alpha Mode bits out of skl_plane_ctl_format into
skl_plane_ctl_alpha, and drop glk_plane_ctl_format, drop initialization
of state->color_ctl on platforms that don't use it, and drop color_ctl
local var. (Ville)

v4: Consolidate skl_plane_ctl_format switch statement on formats that
return the same settings. (Ville)

Signed-off-by: James Ausmus <james.ausmus@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171113181128.2926-1-james.ausmus@intel.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/intel_sprite.c

@@ -263,13 +263,9 @@ skl_update_plane(struct intel_plane *plane,
 
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
-	if (IS_GEMINILAKE(dev_priv) || IS_CANNONLAKE(dev_priv)) {
+	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
 		I915_WRITE_FW(PLANE_COLOR_CTL(pipe, plane_id),
-			      PLANE_COLOR_PIPE_GAMMA_ENABLE |
-			      PLANE_COLOR_PIPE_CSC_ENABLE |
-			      PLANE_COLOR_PLANE_GAMMA_DISABLE);
-	}
-
+			      plane_state->color_ctl);
 	if (key->flags) {
 		I915_WRITE_FW(PLANE_KEYVAL(pipe, plane_id), key->min_value);
 		I915_WRITE_FW(PLANE_KEYMAX(pipe, plane_id), key->max_value);
@@ -978,6 +974,9 @@ intel_check_sprite_plane(struct intel_plane *plane,
 		state->ctl = g4x_sprite_ctl(crtc_state, state);
 	}
 
+	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
+		state->color_ctl = glk_plane_color_ctl(crtc_state, state);
+
 	return 0;
 }