[PATCH] gspca: Try a less bandwidth-intensive alt setting.

[Sarah Sharp]

Under OHCI, UHCI, and EHCI, if an alternate interface setting took too
much of the bus bandwidth, then submit_urb() would fail.  The xHCI host
controller does bandwidth checking when the alternate interface setting is
installed, so usb_set_interface() can fail.  If it does, try the next
alternate interface setting.

Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Tested-by:  Andiry Xu <andiry.xu@xxxxxxx>
---
 drivers/media/video/gspca/gspca.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 222af47..6de3117 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -643,6 +643,7 @@ static struct usb_host_endpoint *get_ep(struct gspca_dev *gspca_dev)
 	xfer = gspca_dev->cam.bulk ? USB_ENDPOINT_XFER_BULK
 				   : USB_ENDPOINT_XFER_ISOC;
 	i = gspca_dev->alt;			/* previous alt setting */
+find_alt:
 	if (gspca_dev->cam.reverse_alts) {
 		while (++i < gspca_dev->nbalt) {
 			ep = alt_xfer(&intf->altsetting[i], xfer);
@@ -666,10 +667,11 @@ static struct usb_host_endpoint *get_ep(struct gspca_dev *gspca_dev)
 	if (gspca_dev->nbalt > 1) {
 		gspca_input_destroy_urb(gspca_dev);
 		ret = usb_set_interface(gspca_dev->dev, gspca_dev->iface, i);
-		if (ret < 0) {
-			err("set alt %d err %d", i, ret);
-			ep = NULL;
-		}
+		/* xHCI hosts will reject set interface requests
+		 * if they take too much bandwidth, so try again.
+		 */
+		if (ret < 0)
+			goto find_alt;
 		gspca_input_create_urb(gspca_dev);
 	}
 	return ep;
-- 
1.6.3.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/