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path: root/drivers/usb/core/urb.c
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Diffstat (limited to 'drivers/usb/core/urb.c')
-rw-r--r--drivers/usb/core/urb.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 3376055..0885d4a 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -241,6 +241,12 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
* If the USB subsystem can't allocate sufficient bandwidth to perform
* the periodic request, submitting such a periodic request should fail.
*
+ * For devices under xHCI, the bandwidth is reserved at configuration time, or
+ * when the alt setting is selected. If there is not enough bus bandwidth, the
+ * configuration/alt setting request will fail. Therefore, submissions to
+ * periodic endpoints on devices under xHCI should never fail due to bandwidth
+ * constraints.
+ *
* Device drivers must explicitly request that repetition, by ensuring that
* some URB is always on the endpoint's queue (except possibly for short
* periods during completion callacks). When there is no longer an urb
@@ -351,6 +357,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
if (xfertype == USB_ENDPOINT_XFER_ISOC) {
int n, len;
+ /* FIXME SuperSpeed isoc endpoints have up to 16 bursts */
/* "high bandwidth" mode, 1-3 packets/uframe? */
if (dev->speed == USB_SPEED_HIGH) {
int mult = 1 + ((max >> 11) & 0x03);
@@ -426,6 +433,11 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
return -EINVAL;
/* too big? */
switch (dev->speed) {
+ case USB_SPEED_SUPER: /* units are 125us */
+ /* Handle up to 2^(16-1) microframes */
+ if (urb->interval > (1 << 15))
+ return -EINVAL;
+ max = 1 << 15;
case USB_SPEED_HIGH: /* units are microframes */
/* NOTE usb handles 2^15 */
if (urb->interval > (1024 * 8))
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