Commit 4e400034 authored Apr 10, 2021 by Chunfeng Yun Committed by Greg Kroah-Hartman Jun 03, 2021

usb: core: reduce power-on-good delay time of root hub



commit 90d28fb53d4a51299ff324dede015d5cb11b88a2 upstream.

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

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1618017645-12259-1-git-send-email-chunfeng.yun@mediatek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 210946e5

drivers/usb/core/hub.h

+4 −2

Original line number	Original line	Diff line number	Diff line
	@@ -146,7 +146,9 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
	{		{
	unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;		unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;

	/* Wait at least 100 msec for power to become stable */		if (!hub->hdev->parent) /* root hub */
			return delay;
			else /* Wait at least 100 msec for power to become stable */
	return max(delay, 100U);		return max(delay, 100U);
	}		}