diff options
| -rw-r--r-- | drivers/media/video/uvc/uvc_video.c | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c index 9a9802830d4..e8cc0a9ddad 100644 --- a/drivers/media/video/uvc/uvc_video.c +++ b/drivers/media/video/uvc/uvc_video.c @@ -924,10 +924,8 @@ static int uvc_init_video_bulk(struct uvc_streaming *stream, static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags) { struct usb_interface *intf = stream->intf; - struct usb_host_interface *alts; - struct usb_host_endpoint *ep = NULL; - int intfnum = stream->intfnum; - unsigned int bandwidth, psize, i; + struct usb_host_endpoint *ep; + unsigned int i; int ret; stream->last_fid = -1; @@ -936,6 +934,12 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags) stream->bulk.payload_size = 0; if (intf->num_altsetting > 1) { + struct usb_host_endpoint *best_ep = NULL; + unsigned int best_psize = 3 * 1024; + unsigned int bandwidth; + unsigned int uninitialized_var(altsetting); + int intfnum = stream->intfnum; + /* Isochronous endpoint, select the alternate setting. */ bandwidth = stream->ctrl.dwMaxPayloadTransferSize; @@ -949,6 +953,9 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags) } for (i = 0; i < intf->num_altsetting; ++i) { + struct usb_host_interface *alts; + unsigned int psize; + alts = &intf->altsetting[i]; ep = uvc_find_endpoint(alts, stream->header.bEndpointAddress); @@ -958,21 +965,27 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags) /* Check if the bandwidth is high enough. */ psize = le16_to_cpu(ep->desc.wMaxPacketSize); psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3)); - if (psize >= bandwidth) - break; + if (psize >= bandwidth && psize <= best_psize) { + altsetting = i; + best_psize = psize; + best_ep = ep; + } } - if (i >= intf->num_altsetting) { + if (best_ep == NULL) { uvc_trace(UVC_TRACE_VIDEO, "No fast enough alt setting " "for requested bandwidth.\n"); return -EIO; } - ret = usb_set_interface(stream->dev->udev, intfnum, i); + uvc_trace(UVC_TRACE_VIDEO, "Selecting alternate setting %u " + "(%u B/frame bandwidth).\n", altsetting, best_psize); + + ret = usb_set_interface(stream->dev->udev, intfnum, altsetting); if (ret < 0) return ret; - ret = uvc_init_video_isoc(stream, ep, gfp_flags); + ret = uvc_init_video_isoc(stream, best_ep, gfp_flags); } else { /* Bulk endpoint, proceed to URB initialization. */ ep = uvc_find_endpoint(&intf->altsetting[0], |