drm/meson: overlay: setup overlay for Amlogic FBC Scatter Memory layout

Setup the Amlogic FBC decoder for the VD1 video overlay plane to use
read the FBC header as Scatter Memory layout reference.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703080728.25207-6-narmstrong@baylibre.com

drivers/gpu/drm/meson/meson_overlay.c

@@ -490,6 +490,10 @@ static void meson_overlay_atomic_update(struct drm_plane *plane,
 						AMLOGIC_FBC_OPTION_MEM_SAVING))
 			priv->viu.vd1_afbc_mode |= AFBC_BLK_MEM_MODE;
 
+		if ((fb->modifier & __fourcc_mod_amlogic_layout_mask) ==
+				AMLOGIC_FBC_LAYOUT_SCATTER)
+			priv->viu.vd1_afbc_mode |= AFBC_SCATTER_MODE;
+
 		priv->viu.vd1_afbc_en = 0x1600 | AFBC_DEC_ENABLE;
 
 		priv->viu.vd1_afbc_conv_ctrl = AFBC_CONV_LBUF_LEN(256);
@@ -675,23 +679,32 @@ static void meson_overlay_atomic_update(struct drm_plane *plane,
 	}
 
 	if (priv->viu.vd1_afbc) {
-		/* Default mode is 4k per superblock */
-		unsigned long block_size = 4096;
-		unsigned long body_size;
-
-		/* 8bit mem saving mode is 3072bytes per superblock */
-		if (priv->viu.vd1_afbc_mode & AFBC_BLK_MEM_MODE)
-			block_size = 3072;
-
-		body_size = (ALIGN(priv->viu.vd1_stride0, 64) / 64) *
-			    (ALIGN(priv->viu.vd1_height0, 32) / 32) *
-			    block_size;
-
-		priv->viu.vd1_afbc_body_addr = priv->viu.vd1_addr0 >> 4;
-
-		/* Header is after body content */
-		priv->viu.vd1_afbc_head_addr = (priv->viu.vd1_addr0 +
-						body_size) >> 4;
+		if (priv->viu.vd1_afbc_mode & AFBC_SCATTER_MODE) {
+			/*
+			 * In Scatter mode, the header contains the physical
+			 * body content layout, thus the body content
+			 * size isn't needed.
+			 */
+			priv->viu.vd1_afbc_head_addr = priv->viu.vd1_addr0 >> 4;
+			priv->viu.vd1_afbc_body_addr = 0;
+		} else {
+			/* Default mode is 4k per superblock */
+			unsigned long block_size = 4096;
+			unsigned long body_size;
+
+			/* 8bit mem saving mode is 3072bytes per superblock */
+			if (priv->viu.vd1_afbc_mode & AFBC_BLK_MEM_MODE)
+				block_size = 3072;
+
+			body_size = (ALIGN(priv->viu.vd1_stride0, 64) / 64) *
+				    (ALIGN(priv->viu.vd1_height0, 32) / 32) *
+				    block_size;
+
+			priv->viu.vd1_afbc_body_addr = priv->viu.vd1_addr0 >> 4;
+			/* Header is after body content */
+			priv->viu.vd1_afbc_head_addr = (priv->viu.vd1_addr0 +
+							body_size) >> 4;
+		}
 	}
 
 	priv->viu.vd1_enabled = true;
@@ -754,7 +767,8 @@ static bool meson_overlay_format_mod_supported(struct drm_plane *plane,
 			return false;
 		}
 
-		if (layout != AMLOGIC_FBC_LAYOUT_BASIC) {
+		if (layout != AMLOGIC_FBC_LAYOUT_BASIC &&
+		    layout != AMLOGIC_FBC_LAYOUT_SCATTER) {
 			DRM_DEBUG_KMS("%llx invalid layout %x\n",
 				      modifier, layout);
 			return false;
@@ -800,8 +814,11 @@ static const uint32_t supported_drm_formats[] = {
 };
 
 static const uint64_t format_modifiers[] = {
+	DRM_FORMAT_MOD_AMLOGIC_FBC(AMLOGIC_FBC_LAYOUT_SCATTER,
+				   AMLOGIC_FBC_OPTION_MEM_SAVING),
 	DRM_FORMAT_MOD_AMLOGIC_FBC(AMLOGIC_FBC_LAYOUT_BASIC,
 				   AMLOGIC_FBC_OPTION_MEM_SAVING),
+	DRM_FORMAT_MOD_AMLOGIC_FBC(AMLOGIC_FBC_LAYOUT_SCATTER, 0),
 	DRM_FORMAT_MOD_AMLOGIC_FBC(AMLOGIC_FBC_LAYOUT_BASIC, 0),
 	DRM_FORMAT_MOD_LINEAR,
 	DRM_FORMAT_MOD_INVALID,