From 5444ca9d5fb255ea35fc60bf1cb27d29135cfbf3 Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Wed, 2 Jun 2010 14:18:29 +0200
Subject: Align userspace buffers to a page size boundary
Some devices need userspace buffers to be page-aligned. Use the
posix_memalign function instead of malloc to allocate page-aligned
buffers.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
yavta.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/yavta.c b/yavta.c
index 3d42915..63d96e3 100644
--- a/yavta.c
+++ b/yavta.c
@@ -270,6 +270,7 @@ static int video_alloc_buffers(struct device *dev, int nbufs)
{
struct v4l2_requestbuffers rb;
struct v4l2_buffer buf;
+ int page_size;
void **bufmem;
unsigned int i;
int ret;
@@ -291,6 +292,8 @@ static int video_alloc_buffers(struct device *dev, int nbufs)
if (bufmem == NULL)
return -ENOMEM;
+ page_size = getpagesize();
+
/* Map the buffers. */
for (i = 0; i < rb.count; ++i) {
memset(&buf, 0, sizeof buf);
@@ -315,9 +318,9 @@ static int video_alloc_buffers(struct device *dev, int nbufs)
break;
case V4L2_MEMORY_USERPTR:
- bufmem[i] = malloc(buf.length);
- if (bufmem[i] == NULL) {
- printf("Unable to allocate buffer %u (%d)\n", i, errno);
+ ret = posix_memalign(&bufmem[i], page_size, buf.length);
+ if (ret < 0) {
+ printf("Unable to allocate buffer %u (%d)\n", i, ret);
return -ENOMEM;
}
printf("Buffer %u allocated at address %p.\n", i, bufmem[i]);
--
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