usb: hub: Disable USB 3 device initiated lpm if exit latency is too high
The device initiated link power management U1/U2 states should not be enabled in case the system exit latency plus one bus interval (125us) is greater than the shortest service interval of any periodic endpoint. This is the case for both U1 and U2 sytstem exit latencies and link states. See USB 3.2 section 9.4.9 "Set Feature" for more details Note, before this patch the host and device initiated U1/U2 lpm states were both enabled with lpm. After this patch it's possible to end up with only host inititated U1/U2 lpm in case the exit latencies won't allow device initiated lpm. If this case we still want to set the udev->usb3_lpm_ux_enabled flag so that sysfs users can see the link may go to U1/U2. Signed-off-by:Mathias Nyman <mathias.nyman@linux.intel.com> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20210715150122.1995966-2-mathias.nyman@linux.intel.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
1bf2761c
Please register or sign in to comment