According to EHCI specification v1.0, the controller should stabilize the power on a port at most 20 ms after the port power bit transition. So, we put this setting in the virtual descriptor corresponding field, (bPwrOn2PwrGood = 10 => 10 x 2ms = 20ms), this saves about 500ms at each controller initialization/enumeration.
Signed-off-by: Vincent Palatin vpalatin@chromium.org --- drivers/usb/host/ehci-hcd.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 2197119..caa0cfb 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -48,7 +48,7 @@ static struct descriptor { 0x29, /* bDescriptorType: hub descriptor */ 2, /* bNrPorts -- runtime modified */ 0, /* wHubCharacteristics */ - 0xff, /* bPwrOn2PwrGood */ + 10, /* bPwrOn2PwrGood */ 0, /* bHubCntrCurrent */ {}, /* Device removable */ {} /* at most 7 ports! XXX */