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 <[email protected]> Signed-off-by: Chunfeng Yun <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
Roynas-Android-Playground · Jun 3, 2021 · 5250e36 · 5250e36
1 parent 55ac0bb
commit 5250e36
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
@@ -152,8 +152,10 @@ 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,