Files
linux/drivers/usb/host
Mathias Nyman cacfa255be xhci: Prevent U1/U2 link pm states if exit latency is too long
commit 0472bf06c6 upstream.

Don't allow USB3 U1 or U2 if the latency to wake up from the U-state
reaches the service interval for a periodic endpoint.

This is according to xhci 1.1 specification section 4.23.5.2 extra note:

"Software shall ensure that a device is prevented from entering a U-state
 where its worst case exit latency approaches the ESIT."

Allowing too long exit latencies for periodic endpoint confuses xHC
internal scheduling, and new devices may fail to enumerate with a
"Not enough bandwidth for new device state" error from the host.

Cc: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-13 09:18:52 +01:00
..
2016-11-21 17:33:40 +01:00
2016-12-08 17:50:09 +01:00
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