linux-kernel - [PATCH 1/2] xhci: Return if xHCI doesn't support LPM

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Message-Id: <20200520101811.2623-1-kai.heng.feng@canonical.com>
Date:   Wed, 20 May 2020 18:18:10 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     mathias.nyman@...el.com
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org (open list:USB XHCI DRIVER),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/2] xhci: Return if xHCI doesn't support LPM

Just return if xHCI is quirked to disable LPM. We can save some time
from reading registers and doing spinlocks.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/usb/host/xhci.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index bee5deccc83d..14181a7ea375 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4390,6 +4390,9 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 	int		hird, exit_latency;
 	int		ret;
 
+	if (xhci->quirks & XHCI_HW_LPM_DISABLE)
+		return -EPERM;
+
 	if (hcd->speed >= HCD_USB3 || !xhci->hw_lpm_support ||
 			!udev->lpm_capable)
 		return -EPERM;
@@ -4412,7 +4415,7 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 	xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n",
 			enable ? "enable" : "disable", port_num + 1);
 
-	if (enable && !(xhci->quirks & XHCI_HW_LPM_DISABLE)) {
+	if (enable) {
 		/* Host supports BESL timeout instead of HIRD */
 		if (udev->usb2_hw_lpm_besl_capable) {
 			/* if device doesn't have a preferred BESL value use a
-- 
2.17.1