V4L/DVB (8209): uvcvideo: Don't free URB buffers on suspend.

All submitted URBs must be killed at suspend time, but URB buffers don't have
to be freed. Avoiding a free on suspend/reallocate on resume lowers the presure
on system memory.

Signed-off-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/video/uvc/uvc_video.c

···
 }
 
 /*
+ * Free transfer buffers.
+ */
+static void uvc_free_urb_buffers(struct uvc_video_device *video)
+{
+	unsigned int i;
+
+	for (i = 0; i < UVC_URBS; ++i) {
+		if (video->urb_buffer[i]) {
+			usb_buffer_free(video->dev->udev, video->urb_size,
+				video->urb_buffer[i], video->urb_dma[i]);
+			video->urb_buffer[i] = NULL;
+		}
+	}
+
+	video->urb_size = 0;
+}
+
+/*
+ * Allocate transfer buffers. This function can be called with buffers
+ * 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.
+ */
+static int uvc_alloc_urb_buffers(struct uvc_video_device *video,
+	unsigned int size)
+{
+	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;
+		}
+	}
+
+	video->urb_size = size;
+	return 0;
+}
+
+/*
  * Uninitialize isochronous/bulk URBs and free transfer buffers.
  */
-static void uvc_uninit_video(struct uvc_video_device *video)
+static void uvc_uninit_video(struct uvc_video_device *video, int free_buffers)
 {
 	struct urb *urb;
 	unsigned int i;
···
 			continue;
 
 		usb_kill_urb(urb);
-		/* urb->transfer_buffer_length is not touched by USB core, so
-		 * we can use it here as the buffer length.
-		 */
-		if (video->urb_buffer[i]) {
-			usb_buffer_free(video->dev->udev,
-				urb->transfer_buffer_length,
-				video->urb_buffer[i], urb->transfer_dma);
-			video->urb_buffer[i] = NULL;
-		}
-
 		usb_free_urb(urb);
 		video->urb[i] = NULL;
 	}
+
+	if (free_buffers)
+		uvc_free_urb_buffers(video);
 }
 
 /*
···
 
 	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) {
-			uvc_uninit_video(video);
-			return -ENOMEM;
-		}
-
-		video->urb_buffer[i] = usb_buffer_alloc(video->dev->udev,
-			size, gfp_flags, &urb->transfer_dma);
-		if (video->urb_buffer[i] == NULL) {
-			usb_free_urb(urb);
-			uvc_uninit_video(video);
+			uvc_uninit_video(video, 1);
 			return -ENOMEM;
 		}
 
···
 		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
 		urb->interval = ep->desc.bInterval;
 		urb->transfer_buffer = video->urb_buffer[i];
+		urb->transfer_dma = video->urb_dma[i];
 		urb->complete = uvc_video_complete;
 		urb->number_of_packets = npackets;
 		urb->transfer_buffer_length = size;
···
 	if (size > psize * UVC_MAX_ISO_PACKETS)
 		size = psize * UVC_MAX_ISO_PACKETS;
 
+	if (uvc_alloc_urb_buffers(video, size) < 0)
+		return -ENOMEM;
+
 	pipe = usb_rcvbulkpipe(video->dev->udev, ep->desc.bEndpointAddress);
 
 	for (i = 0; i < UVC_URBS; ++i) {
 		urb = usb_alloc_urb(0, gfp_flags);
 		if (urb == NULL) {
-			uvc_uninit_video(video);
-			return -ENOMEM;
-		}
-
-		video->urb_buffer[i] = usb_buffer_alloc(video->dev->udev,
-			size, gfp_flags, &urb->transfer_dma);
-		if (video->urb_buffer[i] == NULL) {
-			usb_free_urb(urb);
-			uvc_uninit_video(video);
+			uvc_uninit_video(video, 1);
 			return -ENOMEM;
 		}
 
···
 			video->urb_buffer[i], size, uvc_video_complete,
 			video);
 		urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
+		urb->transfer_dma = video->urb_dma[i];
 
 		video->urb[i] = urb;
 	}
···
 		if ((ret = usb_submit_urb(video->urb[i], gfp_flags)) < 0) {
 			uvc_printk(KERN_ERR, "Failed to submit URB %u "
 					"(%d).\n", i, ret);
-			uvc_uninit_video(video);
+			uvc_uninit_video(video, 1);
 			return ret;
 		}
 	}
···
 		return 0;
 
 	video->frozen = 1;
-	uvc_uninit_video(video);
+	uvc_uninit_video(video, 0);
 	usb_set_interface(video->dev->udev, video->streaming->intfnum, 0);
 	return 0;
 }
···
 	int ret;
 
 	if (!enable) {
-		uvc_uninit_video(video);
+		uvc_uninit_video(video, 1);
 		usb_set_interface(video->dev->udev,
 			video->streaming->intfnum, 0);
 		uvc_queue_enable(&video->queue, 0);

drivers/media/video/uvc/uvcvideo.h

···
 
 	struct urb *urb[UVC_URBS];
 	char *urb_buffer[UVC_URBS];
+	dma_addr_t urb_dma[UVC_URBS];
+	unsigned int urb_size;
 
 	__u8 last_fid;
 };