gralloc4: Update YV12 alignment to conform to platform contract

After this patch, GPU usages are not guaranteed to conform to platform's
contract, but others will be.

Bug: 274375412
Test: gfx-gralloc-alloc-test
Test: Manually tested GPU rendering using map-graphics-buffer tool
Change-Id: I3a0202c61d3e558595a856ec150d12be5a7220fc

1 files changed, 12 insertions, 18 deletions

diff --git a/gralloc4/src/core/mali_gralloc_bufferallocation.cpp b/gralloc4/src/core/mali_gralloc_bufferallocation.cpp
index 7355930..289db0b 100644
--- a/gralloc4/src/core/mali_gralloc_bufferallocation.cpp
+++ b/gralloc4/src/core/mali_gralloc_bufferallocation.cpp
@@ -450,20 +450,14 @@ static void update_yv12_stride(int8_t plane,
                                uint32_t stride_align,
                                uint32_t * byte_stride)
 {
-	if (plane == 0)
-	{
-		*byte_stride = GRALLOC_ALIGN(luma_stride, GRALLOC_ALIGN(stride_align, 32));
-	}
-	else
-	{
-		/*
-		 * Derive chroma stride from luma and verify it is:
-		 * 1. Aligned to "1/2*lcm(hw_align, cpu_align)"
-		 * 2. Multiple of 16px (16 bytes)
-		 */
-		*byte_stride = luma_stride / 2;
-		assert(*byte_stride == GRALLOC_ALIGN(*byte_stride, GRALLOC_ALIGN(stride_align / 2, 16)));
-		assert(*byte_stride & 15 == 0);
+	// https://developer.android.com/reference/android/graphics/ImageFormat#YV12
+	if (plane == 0) {
+		// stride_align has to be honored as GPU alignment still requires the format to be
+		// 64 bytes aligned. Though that does not break the contract as long as the
+		// horizontal stride for chroma is half the luma stride and aligned to 16.
+		*byte_stride = GRALLOC_ALIGN(luma_stride, GRALLOC_ALIGN(stride_align, 16));
+	} else {
+		*byte_stride = GRALLOC_ALIGN(luma_stride / 2, 16);
 	}
 }
 #endif
@@ -647,10 +641,10 @@ static void calc_allocation_size(const int width,
 			/*
 			 * Update YV12 stride with both CPU & HW usage due to constraint of chroma stride.
 			 * Width is anyway aligned to 16px for luma and chroma (has_cpu_usage).
-                         *
-                         * Note: To prevent luma stride misalignment with GPU stride alignment.
-                         * The luma plane will maintain the same `stride` size, and the chroma plane
-                         * will align to `stride/2`.
+			 *
+			 * Note: To prevent luma stride misalignment with GPU stride alignment.
+			 * The luma plane will maintain the same `stride` size, and the chroma plane
+			 * will align to `stride/2`.
 			 */
 			if (format.id == MALI_GRALLOC_FORMAT_INTERNAL_YV12 && has_hw_usage && has_cpu_usage)
 			{