drm/i915/dsi: skip unknown elements for sequence block v3+

The sequence block has sizes of elements after the operation byte since
sequence block v3. Use it to skip elements we don't support yet.

v2: remove redundant exec_elem[operation_byte] check (Daniel)
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452006408-27688-1-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/intel_dsi_panel_vbt.c

@@ -283,31 +283,35 @@ static void generic_exec_sequence(struct intel_dsi *intel_dsi, const u8 *data)
 	if (dev_priv->vbt.dsi.seq_version >= 3)
 		data += 4;
 
-	/* parse each byte till we reach end of sequence byte - 0x00 */
 	while (1) {
 		u8 operation_byte = *data++;
-		if (operation_byte >= ARRAY_SIZE(exec_elem) ||
-		    !exec_elem[operation_byte]) {
-			DRM_ERROR("Unsupported MIPI operation byte %u\n",
-				  operation_byte);
-			return;
-		}
+		u8 operation_size = 0;
+
+		if (operation_byte == MIPI_SEQ_ELEM_END)
+			break;
+
+		if (operation_byte < ARRAY_SIZE(exec_elem))
 			mipi_elem_exec = exec_elem[operation_byte];
+		else
+			mipi_elem_exec = NULL;
 
-		/* Skip Size of Operation. */
+		/* Size of Operation. */
 		if (dev_priv->vbt.dsi.seq_version >= 3)
-			data++;
+			operation_size = *data++;
 
-		/* execute the element specific rotines */
+		if (mipi_elem_exec) {
 			data = mipi_elem_exec(intel_dsi, data);
-
-		/*
-		 * After processing the element, data should point to
-		 * next element or end of sequence
-		 * check if have we reached end of sequence
-		 */
-		if (*data == 0x00)
-			break;
+		} else if (operation_size) {
+			/* We have size, skip. */
+			DRM_DEBUG_KMS("Unsupported MIPI operation byte %u\n",
+				      operation_byte);
+			data += operation_size;
+		} else {
+			/* No size, can't skip without parsing. */
+			DRM_ERROR("Unsupported MIPI operation byte %u\n",
+				  operation_byte);
+			return;
+		}
 	}
 }