minigbm: align first plane to 64 bytes

The chroma stride of Android YV12 buffers is required to be
aligned to 16 bytes (see <system/graphics.h>).

Additionally, the size of the ARM L1 cache line is 64-bytes
(see chrome-os-partner:45777).

Let's always align the first plane to 64 bytes. The chroma strides
will be aligned to 32 bytes in that case.

BUG=chromium:616275
TEST=

ImageReaderDecoderTest#testGoogH264ImageReader

passes on veyron_minnie-cheets.

Change-Id: I87a309ce0612bf8c5be8f8e47dad3da10d61a081
Reviewed-on: https://chromium-review.googlesource.com/441912
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/rockchip.c b/rockchip.c
index 30b6822..140ec93 100644
--- a/rockchip.c
+++ b/rockchip.c
@@ -142,6 +142,13 @@ static int rockchip_bo_create_with_modifiers(struct bo *bo,
 			fprintf(stderr, "no usable modifier found\n");
 			return -1;
 		}
+
+		/*
+		 * Since the ARM L1 cache line size is 64 bytes, align to that
+		 * as a performance optimization.
+		 */
+		uint32_t bytes_per_pixel = drv_stride_from_format(format, 1, 0);
+		width = ALIGN(width, DIV_ROUND_UP(64, bytes_per_pixel));
 		drv_bo_from_format(bo, width, height, format);
 	}