Re: [PATCH] uvc: more buffers

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Oliver,

Thank you for the patch.

On Friday 09 August 2013 15:11:36 oliver@neukum.org wrote:
> From: Oliver Neukum <oneukum@suse.de>
> 
> This is necessary to let the new generation of cameras from LiteOn used in
> Haswell ULT notebook operate. Otherwise the images will be truncated.

Could you please post the lsusb -v output for the device ?

Why does it need more buffers, is it a superspeed webcam ?

> Signed-off-by: Oliver Neukum <oneukum@suse.de>
> ---
>  drivers/media/usb/uvc/uvcvideo.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvcvideo.h
> b/drivers/media/usb/uvc/uvcvideo.h index 9e35982..9f1930b 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -114,9 +114,9 @@
>  /* Number of isochronous URBs. */
>  #define UVC_URBS		5
>  /* Maximum number of packets per URB. */
> -#define UVC_MAX_PACKETS		32
> +#define UVC_MAX_PACKETS		128

That would mean up to 384KiB per URB. While not unreasonable, I'd like to know 
how much data your camera produces to require this.

>  /* Maximum number of video buffers. */
> -#define UVC_MAX_VIDEO_BUFFERS	32
> +#define UVC_MAX_VIDEO_BUFFERS	128

I don't think your camera really needs more than 32 V4L2 (full frame) buffers 
:-)

>  /* Maximum status buffer size in bytes of interrupt URB. */
>  #define UVC_MAX_STATUS_SIZE	16
-- 
Regards,

Laurent Pinchart