@@ -1652,6 +1652,19 @@ static inline int v4l_queue_munmap_bufs(struct v4l_fd *f, struct v4l_queue *q,
return 0;
}
+static inline void *userptr_malloc(size_t size)
+{
+ int v4l2_page_size = getpagesize();
+ void *ptr_addr = 0;
+
+ int ret = posix_memalign(&ptr_addr, v4l2_page_size, size);
+ if (ret != 0) {
+ fprintf(stderr, "malloc via posix_memalign failed\n");
+ return 0;
+ }
+ return ptr_addr;
+}
+
static inline int v4l_queue_alloc_bufs(struct v4l_fd *f,
struct v4l_queue *q, unsigned from)
{
@@ -1661,7 +1674,7 @@ static inline int v4l_queue_alloc_bufs(struct v4l_fd *f,
return 0;
for (b = from; b < v4l_queue_g_buffers(q); b++) {
for (p = 0; p < v4l_queue_g_num_planes(q); p++) {
- void *m = malloc(v4l_queue_g_length(q, p));
+ void *m = userptr_malloc(v4l_queue_g_length(q, p));
if (m == NULL)
return errno;
When dealing with a userptr pointing to a buffer in userspace, videobuf2 swaps the corresponding physical pages with other pages so we have a contiguous area of memory for DMA. This only works if the userptr is page aligned. The current way of allocating user buffers using malloc only guarantees alignment up to `alignof(max_align_t)`, which is usually 16. So replace malloc with posix_memalign to ensure the returned pointer is on a page boundary. Signed-off-by: Brandon Cheo Fusi <fusibrandon13@gmail.com> --- utils/common/v4l-helpers.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)