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authorAl Cooper <alcooperx@gmail.com>2011-08-18 10:28:29 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-09-23 20:07:47 -0300
commit3e0ac6717b0a2593243ef3850025a42cb199880f (patch)
tree24726342cb2e85848eb0d24e9a34f4c645773706 /drivers/media/video/uvc
parent227bd5b3539a50290ec48b90c42c40cc7ae27191 (diff)
[media] media: Fix a UVC performance problem on systems with non-coherent DMA
The UVC driver uses usb_alloc_coherent() to allocate DMA data buffers. On systems without coherent DMA this ends up allocating buffers in uncached memory. The subsequent memcpy's done to coalesce the DMA chunks into contiguous buffers then run VERY slowly. On a MIPS test system the memcpy is about 200 times slower. This issue prevents the system from keeping up with 720p YUYV data at 10fps. The following patch uses kmalloc to alloc the DMA buffers instead of usb_alloc_coherent on systems without coherent DMA. With this patch the system was easily able to keep up with 720p at 10fps. Signed-off-by: Al Cooper <alcooperx@gmail.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video/uvc')
-rw-r--r--drivers/media/video/uvc/uvc_video.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c
index ffd1158628b6..b015e8e5e8b0 100644
--- a/drivers/media/video/uvc/uvc_video.c
+++ b/drivers/media/video/uvc/uvc_video.c
@@ -790,8 +790,12 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream)
for (i = 0; i < UVC_URBS; ++i) {
if (stream->urb_buffer[i]) {
+#ifndef CONFIG_DMA_NONCOHERENT
usb_free_coherent(stream->dev->udev, stream->urb_size,
stream->urb_buffer[i], stream->urb_dma[i]);
+#else
+ kfree(stream->urb_buffer[i]);
+#endif
stream->urb_buffer[i] = NULL;
}
}
@@ -831,9 +835,14 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
for (; npackets > 1; npackets /= 2) {
for (i = 0; i < UVC_URBS; ++i) {
stream->urb_size = psize * npackets;
+#ifndef CONFIG_DMA_NONCOHERENT
stream->urb_buffer[i] = usb_alloc_coherent(
stream->dev->udev, stream->urb_size,
gfp_flags | __GFP_NOWARN, &stream->urb_dma[i]);
+#else
+ stream->urb_buffer[i] =
+ kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN);
+#endif
if (!stream->urb_buffer[i]) {
uvc_free_urb_buffers(stream);
break;
@@ -908,10 +917,14 @@ static int uvc_init_video_isoc(struct uvc_streaming *stream,
urb->context = stream;
urb->pipe = usb_rcvisocpipe(stream->dev->udev,
ep->desc.bEndpointAddress);
+#ifndef CONFIG_DMA_NONCOHERENT
urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
+ urb->transfer_dma = stream->urb_dma[i];
+#else
+ urb->transfer_flags = URB_ISO_ASAP;
+#endif
urb->interval = ep->desc.bInterval;
urb->transfer_buffer = stream->urb_buffer[i];
- urb->transfer_dma = stream->urb_dma[i];
urb->complete = uvc_video_complete;
urb->number_of_packets = npackets;
urb->transfer_buffer_length = size;
@@ -969,8 +982,10 @@ static int uvc_init_video_bulk(struct uvc_streaming *stream,
usb_fill_bulk_urb(urb, stream->dev->udev, pipe,
stream->urb_buffer[i], size, uvc_video_complete,
stream);
+#ifndef CONFIG_DMA_NONCOHERENT
urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
urb->transfer_dma = stream->urb_dma[i];
+#endif
stream->urb[i] = urb;
}