Re: usb video capture issue due to uvc_complete callback spends more time

[Felipe Balbi]

On Thu, Mar 28, 2013 at 03:23:46PM +0200, Felipe Balbi wrote:
> Hi,
> 
> On Thu, Mar 28, 2013 at 08:53:03PM +0800, Ming Lei wrote:
> > On Thu, Mar 28, 2013 at 8:30 PM, B, Ravi <ravib...@ti.com> wrote:
> > >
> > > For example, in one iteration I have observed, the time taken by
> > > uvc_video_decode_isoc() was 2175 usec. In this maximum amount of
> > > time was consumed by uvc_video_decode_data() around 1792 usec.
> > 
> > uvc_video_decode_data() is basically a memcpy() from coherent buffer to
> > normal buffer.
> 
> if that's the case, this should show, right ?
> 
> diff --git a/drivers/media/usb/uvc/uvc_video.c 
> b/drivers/media/usb/uvc/uvc_video.c
> index 3394c34..fdba0b7 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -1490,12 +1490,7 @@ 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->complete = uvc_video_complete;
> @@ -1555,10 +1550,6 @@ 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;
>       }

actually this is more correct I guess:

diff --git a/drivers/media/usb/uvc/uvc_video.c 
b/drivers/media/usb/uvc/uvc_video.c
index 3394c34..5c0e3a6 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1387,14 +1387,8 @@ 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;
@@ -1490,12 +1484,7 @@ 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->complete = uvc_video_complete;
@@ -1555,10 +1544,6 @@ 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;
        }

-- 
balbi

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