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Diffstat (limited to 'drivers/usb/core/urb.c')
| -rw-r--r-- | drivers/usb/core/urb.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index 02eb0ef7a4c..0885d4abdc6 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 |