diff --git a/shared-core/i915_dma.c b/shared-core/i915_dma.c
index 80f643cd..6d85e050 100644
--- a/shared-core/i915_dma.c
+++ b/shared-core/i915_dma.c
@@ -306,7 +306,14 @@ static int do_validate_cmd( int cmd )
 		case 0x1c: 
 			return 1;
 		case 0x1d:
-			return (cmd & 0xffff) + 2;
+			switch ((cmd>>16)&0xff) {
+			case 0x3: 
+				return (cmd & 0x1f) + 2;
+			case 0x4: 
+				return (cmd & 0xf) + 2;
+			default:  
+				return (cmd & 0xffff) + 2;
+			}
 		case 0x1e: 
 			if (cmd & (1<<23)) 
 				return (cmd & 0xffff) + 1;
diff --git a/shared/i915_dma.c b/shared/i915_dma.c
index 80f643cd..6d85e050 100644
--- a/shared/i915_dma.c
+++ b/shared/i915_dma.c
@@ -306,7 +306,14 @@ static int do_validate_cmd( int cmd )
 		case 0x1c: 
 			return 1;
 		case 0x1d:
-			return (cmd & 0xffff) + 2;
+			switch ((cmd>>16)&0xff) {
+			case 0x3: 
+				return (cmd & 0x1f) + 2;
+			case 0x4: 
+				return (cmd & 0xf) + 2;
+			default:  
+				return (cmd & 0xffff) + 2;
+			}
 		case 0x1e: 
 			if (cmd & (1<<23)) 
 				return (cmd & 0xffff) + 1;