On Fri, Apr 09, 2021 at 10:39:07AM +0800, Chunfeng Yun wrote:
> Return the exactly delay time given by root hub descriptor,
> this helps to reduce resume time etc.
>
> Due to the root hub descriptor is usually provided by the host
> controller driver, if there is compatibility for a root hub,
> we can fix it easily without affect other root hub
>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/usb/core/hub.h | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> index 73f4482d833a..22ea1f4f2d66 100644
> --- a/drivers/usb/core/hub.h
> +++ b/drivers/usb/core/hub.h
> @@ -148,8 +148,10 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
> {
> unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;
>
> - /* Wait at least 100 msec for power to become stable */
> - return max(delay, 100U);
> + if (!hub->hdev->parent) /* root hub */
> + return delay;
> + else /* Wait at least 100 msec for power to become stable */
> + return max(delay, 100U);
> }
>
> static inline int hub_port_debounce_be_connected(struct usb_hub *hub,
> --
> 2.18.0
>
