drm/i915: Add a platform independent way to get the RC CCS CC plane

On future platforms the index of the color-clear plane will change from
the one used by the GEN12 RC CCS CC modifier, so add a way to retrieve
the index independently of the platform/modifier.

Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020195138.1841242-8-imre.deak@intel.com

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

@@ -8572,10 +8572,14 @@ static void intel_atomic_prepare_plane_clear_colors(struct intel_atomic_state *s
 
 	for_each_new_intel_plane_in_state(state, plane, plane_state, i) {
 		struct drm_framebuffer *fb = plane_state->hw.fb;
+		int cc_plane;
 		int ret;
 
-		if (!fb ||
-		    fb->modifier != I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS_CC)
+		if (!fb)
+			continue;
+
+		cc_plane = intel_fb_rc_ccs_cc_plane(fb);
+		if (cc_plane < 0)
 			continue;
 
 		/*
@@ -8592,7 +8596,7 @@ static void intel_atomic_prepare_plane_clear_colors(struct intel_atomic_state *s
 		 * GPU write on it.
 		 */
 		ret = i915_gem_object_read_from_page(intel_fb_obj(fb),
-						     fb->offsets[2] + 16,
+						     fb->offsets[cc_plane] + 16,
 						     &plane_state->ccval,
 						     sizeof(plane_state->ccval));
 		/* The above could only fail if the FB obj has an unexpected backing store type. */

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

@@ -130,6 +130,7 @@ struct intel_modifier_desc {
 
 #define INTEL_CCS_ANY		(INTEL_CCS_RC | INTEL_CCS_RC_CC | INTEL_CCS_MC)
 		u8 type:3;
+		u8 cc_planes:3;
 	} ccs;
 };
 
@@ -156,6 +157,7 @@ static const struct intel_modifier_desc intel_modifiers[] = {
 		.tiling = I915_TILING_Y,
 
 		.ccs.type = INTEL_CCS_RC_CC,
+		.ccs.cc_planes = BIT(2),
 
 		FORMAT_OVERRIDE(gen12_ccs_cc_formats),
 	}, {
@@ -373,10 +375,29 @@ bool is_gen12_ccs_plane(const struct drm_framebuffer *fb, int plane)
 	return is_gen12_ccs_modifier(fb->modifier) && is_ccs_plane(fb, plane);
 }
 
+/**
+ * intel_fb_rc_ccs_cc_plane: Get the CCS CC color plane index for a framebuffer
+ * @fb: Framebuffer
+ *
+ * Returns:
+ * Returns the index of the color clear plane for @fb, or -1 if @fb is not a
+ * framebuffer using a render compression/color clear modifier.
+ */
+int intel_fb_rc_ccs_cc_plane(const struct drm_framebuffer *fb)
+{
+	const struct intel_modifier_desc *md = lookup_modifier(fb->modifier);
+
+	if (!md->ccs.cc_planes)
+		return -1;
+
+	drm_WARN_ON_ONCE(fb->dev, hweight8(md->ccs.cc_planes) > 1);
+
+	return ilog2((int)md->ccs.cc_planes);
+}
+
 bool is_gen12_ccs_cc_plane(const struct drm_framebuffer *fb, int plane)
 {
-	return fb->modifier == I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS_CC &&
-	       plane == 2;
+	return intel_fb_rc_ccs_cc_plane(fb) == plane;
 }
 
 static bool is_semiplanar_uv_plane(const struct drm_framebuffer *fb, int color_plane)

drivers/gpu/drm/i915/display/intel_fb.h

@@ -31,6 +31,8 @@ bool is_ccs_plane(const struct drm_framebuffer *fb, int plane);
 bool is_gen12_ccs_plane(const struct drm_framebuffer *fb, int plane);
 bool is_gen12_ccs_cc_plane(const struct drm_framebuffer *fb, int plane);
 
+int intel_fb_rc_ccs_cc_plane(const struct drm_framebuffer *fb);
+
 u64 *intel_fb_plane_get_modifiers(struct drm_i915_private *i915,
 				  enum intel_plane_caps plane_caps);
 bool intel_fb_plane_supports_modifier(struct intel_plane *plane, u64 modifier);