usb: host: xhci-plat: enable clk in resume timing

This patch enables the clk in resume timing when device_may_wakeup()
is false. Otherwise, kernel panic happens when R-Car resumes the system
from Suspend-to-RAM because the clk is disabled.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-plat.c

@@ -347,6 +347,7 @@ static int xhci_plat_suspend(struct device *dev)
 {
 	struct usb_hcd	*hcd = dev_get_drvdata(dev);
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
+	int ret;
 
 	/*
 	 * xhci_suspend() needs `do_wakeup` to know whether host is allowed
@@ -356,7 +357,12 @@ static int xhci_plat_suspend(struct device *dev)
 	 * reconsider this when xhci_plat_suspend enlarges its scope, e.g.,
 	 * also applies to runtime suspend.
 	 */
-	return xhci_suspend(xhci, device_may_wakeup(dev));
+	ret = xhci_suspend(xhci, device_may_wakeup(dev));
+
+	if (!device_may_wakeup(dev) && !IS_ERR(xhci->clk))
+		clk_disable_unprepare(xhci->clk);
+
+	return ret;
 }
 
 static int xhci_plat_resume(struct device *dev)
@@ -364,6 +370,9 @@ static int xhci_plat_resume(struct device *dev)
 	struct usb_hcd	*hcd = dev_get_drvdata(dev);
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 
+	if (!device_may_wakeup(dev) && !IS_ERR(xhci->clk))
+		clk_prepare_enable(xhci->clk);
+
 	return xhci_resume(xhci, 0);
 }
 #endif /* CONFIG_PM_SLEEP */