Modified the xHCI roothub descriptor to return USB2.0 extension descriptor Best Effort Service Latency (BESL) and Deep Best Effort Service Latency (DBESL) values when set on the xHCI host. On link power management the BESL and DBESL values are used to estimate L1 exit latency for USB2.0 host and devices. Tools such as PowerTop and lsusb will use BESL and DBESL values to monitor LPM L1 exit latency. Additionally, by presenting the host controller BESL and DBESL values one could check if the BIOS or firmware is setting these values correctly. Currently the root hub device descriptor bcdUSB value is set to zero by the BIOS. Therefore to test this functionality with lsusb, I hard coded the usb2_rh_dev_descriptor (not include on patch) to: bcdUSB 0x01. Alexandra Yates (1): xhci-hub: Roothub USB2.0 descriptor for BESL DBESL drivers/usb/host/xhci-hub.c | 53 +++++++++++++++++++++++++++++++++++++++---- drivers/usb/host/xhci.h | 3 +++ 2 files changed, 51 insertions(+), 5 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
