V4L/DVB (10295): uvcvideo: Retry URB buffers allocation when the system is low on memory.
URB buffers for video transfers are sized to UVC_MAX_PACKETS bulk/isochronous
packets by default. If the system is too low on memory try successively
smaller numbers of packets until allocation succeeds.
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c
index 9bc4705..7ebb895 100644
--- a/drivers/media/video/uvc/uvc_video.c
+++ b/drivers/media/video/uvc/uvc_video.c
@@ -699,27 +699,47 @@
* already allocated when resuming from suspend, in which case it will
* return without touching the buffers.
*
- * Return 0 on success or -ENOMEM when out of memory.
+ * Limit the buffer size to UVC_MAX_PACKETS bulk/isochronous packets. If the
+ * system is too low on memory try successively smaller numbers of packets
+ * until allocation succeeds.
+ *
+ * Return the number of allocated packets on success or 0 when out of memory.
*/
static int uvc_alloc_urb_buffers(struct uvc_video_device *video,
- unsigned int size)
+ unsigned int size, unsigned int psize, gfp_t gfp_flags)
{
+ unsigned int npackets;
unsigned int i;
/* Buffers are already allocated, bail out. */
if (video->urb_size)
return 0;
- for (i = 0; i < UVC_URBS; ++i) {
- video->urb_buffer[i] = usb_buffer_alloc(video->dev->udev,
- size, GFP_KERNEL, &video->urb_dma[i]);
- if (video->urb_buffer[i] == NULL) {
- uvc_free_urb_buffers(video);
- return -ENOMEM;
+ /* Compute the number of packets. Bulk endpoints might transfer UVC
+ * payloads accross multiple URBs.
+ */
+ npackets = DIV_ROUND_UP(size, psize);
+ if (npackets > UVC_MAX_PACKETS)
+ npackets = UVC_MAX_PACKETS;
+
+ /* Retry allocations until one succeed. */
+ for (; npackets > 1; npackets /= 2) {
+ for (i = 0; i < UVC_URBS; ++i) {
+ video->urb_buffer[i] = usb_buffer_alloc(
+ video->dev->udev, psize * npackets,
+ gfp_flags | __GFP_NOWARN, &video->urb_dma[i]);
+ if (!video->urb_buffer[i]) {
+ uvc_free_urb_buffers(video);
+ break;
+ }
+ }
+
+ if (i == UVC_URBS) {
+ video->urb_size = psize * npackets;
+ return npackets;
}
}
- video->urb_size = size;
return 0;
}
@@ -753,29 +773,19 @@
{
struct urb *urb;
unsigned int npackets, i, j;
- __u16 psize;
- __u32 size;
+ u16 psize;
+ u32 size;
- /* Compute the number of isochronous packets to allocate by dividing
- * the maximum video frame size by the packet size. Limit the result
- * to UVC_MAX_ISO_PACKETS.
- */
psize = le16_to_cpu(ep->desc.wMaxPacketSize);
psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3));
-
size = video->streaming->ctrl.dwMaxVideoFrameSize;
- if (size > UVC_MAX_FRAME_SIZE)
- return -EINVAL;
- npackets = DIV_ROUND_UP(size, psize);
- if (npackets > UVC_MAX_ISO_PACKETS)
- npackets = UVC_MAX_ISO_PACKETS;
+ npackets = uvc_alloc_urb_buffers(video, size, psize, gfp_flags);
+ if (npackets == 0)
+ return -ENOMEM;
size = npackets * psize;
- if (uvc_alloc_urb_buffers(video, size) < 0)
- return -ENOMEM;
-
for (i = 0; i < UVC_URBS; ++i) {
urb = usb_alloc_urb(npackets, gfp_flags);
if (urb == NULL) {
@@ -814,25 +824,20 @@
struct usb_host_endpoint *ep, gfp_t gfp_flags)
{
struct urb *urb;
- unsigned int pipe, i;
- __u16 psize;
- __u32 size;
+ unsigned int npackets, pipe, i;
+ u16 psize;
+ u32 size;
- /* Compute the bulk URB size. Some devices set the maximum payload
- * size to a value too high for memory-constrained devices. We must
- * then transfer the payload accross multiple URBs. To be consistant
- * with isochronous mode, allocate maximum UVC_MAX_ISO_PACKETS per bulk
- * URB.
- */
psize = le16_to_cpu(ep->desc.wMaxPacketSize) & 0x07ff;
size = video->streaming->ctrl.dwMaxPayloadTransferSize;
video->bulk.max_payload_size = size;
- if (size > psize * UVC_MAX_ISO_PACKETS)
- size = psize * UVC_MAX_ISO_PACKETS;
- if (uvc_alloc_urb_buffers(video, size) < 0)
+ npackets = uvc_alloc_urb_buffers(video, size, psize, gfp_flags);
+ if (npackets == 0)
return -ENOMEM;
+ size = npackets * psize;
+
if (usb_endpoint_dir_in(&ep->desc))
pipe = usb_rcvbulkpipe(video->dev->udev,
ep->desc.bEndpointAddress);
diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index 027947e..b263987 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -296,10 +296,8 @@
/* Number of isochronous URBs. */
#define UVC_URBS 5
-/* Maximum number of packets per isochronous URB. */
-#define UVC_MAX_ISO_PACKETS 40
-/* Maximum frame size in bytes, for sanity checking. */
-#define UVC_MAX_FRAME_SIZE (16*1024*1024)
+/* Maximum number of packets per URB. */
+#define UVC_MAX_PACKETS 32
/* Maximum number of video buffers. */
#define UVC_MAX_VIDEO_BUFFERS 32
/* Maximum status buffer size in bytes of interrupt URB. */