Commit efdc8a95 authored by Laurent Pinchart's avatar Laurent Pinchart Committed by Mauro Carvalho Chehab
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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: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@skynet.be>
Reviewed-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent f61d1d8a

drivers/media/video/uvc/uvc_video.c

+42 −37
Original line number Diff line number Diff line
@@ -699,27 +699,47 @@ static void uvc_free_urb_buffers(struct uvc_video_device *video) 
 * 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;



	/* 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,

			size, GFP_KERNEL, &video->urb_dma[i]);

		if (video->urb_buffer[i] == NULL) {

			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);

			return -ENOMEM;

				break;

			}

		}



		if (i == UVC_URBS) {

			video->urb_size = psize * npackets;

			return npackets;

		}

	}



	video->urb_size = size;

	return 0;

}
@@ -753,29 +773,19 @@ static int uvc_init_video_isoc(struct uvc_video_device *video, 
{

	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 @@ static int uvc_init_video_bulk(struct uvc_video_device *video, 
	struct usb_host_endpoint *ep, gfp_t gfp_flags)

{

	struct urb *urb;

	unsigned int 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.

	 */

	unsigned int npackets, pipe, i;

	u16 psize;

	u32 size;



	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);

drivers/media/video/uvc/uvcvideo.h

+2 −4
Original line number Diff line number Diff line
@@ -296,10 +296,8 @@ struct uvc_xu_control { 


/* 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. */