sna: Constrain GPU pixmaps to always fit within the blitter

Otherwise we end up always doing expensive readbacks where we would
obviously prefer it if we simply used cached memory for the CPU
operation and then upload.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 21 insertions, 6 deletions

diff --git a/src/sna/kgem.c b/src/sna/kgem.c
index b0e76b7a..29f572b8 100644
--- a/src/sna/kgem.c
+++ b/src/sna/kgem.c
@@ -443,16 +443,31 @@ static uint32_t kgem_surface_size(struct kgem *kgem,
 		break;
 	}
 
+	/* If it is too wide for the blitter, don't even bother.  */
 	*pitch = ALIGN(width * bpp / 8, tile_width);
-	if (kgem->gen < 40 && tiling != I915_TILING_NONE) {
-		if (*pitch > 8192)
+	if (kgem->gen < 40) {
+		if(tiling != I915_TILING_NONE) {
+			if (*pitch > 8192)
+				return 0;
+			for (size = tile_width; size < *pitch; size <<= 1)
+				;
+			*pitch = size;
+		} else {
+			if (*pitch >= 32768)
+				return 0;
+		}
+	} else {
+		int limit = 32768;
+		if (tiling)
+			limit *= 4;
+		if (*pitch >= limit)
 			return 0;
-		for (size = tile_width; size < *pitch; size <<= 1)
-			;
-		*pitch = size;
 	}
+	height = ALIGN(height, tile_height);
+	if (height >= 65536)
+		return 0;
 
-	size = *pitch * ALIGN(height, tile_height);
+	size = *pitch * height;
 	if (kgem->has_relaxed_fencing || tiling == I915_TILING_NONE)
 		return ALIGN(size, PAGE_SIZE);