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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
To:     mathias.nyman@intel.com
Cc:     Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org (open list:USB XHCI DRIVER),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH 1/2] xhci: Suspend ports to U3 directly from U1 or U2
Date:   Wed, 10 Jun 2020 14:42:30 +0800
Message-Id: <20200610064231.9454-1-kai.heng.feng@canonical.com>
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Sender: linux-kernel-owner@vger.kernel.org
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xHCI spec "4.15.1 Port Suspend" states that port can be put to U3 as long
as Enabled bit is set and from U0, U1 or U2 state.

Currently only USB_PORT_FEAT_LINK_STATE puts port to U3 directly, let's
do the same for USB_PORT_FEAT_SUSPEND and bus suspend case.

This is particularly useful for USB2 devices, which may take a very long
time to switch USB2 LPM on and off.

Suggested-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/usb/host/xhci-hub.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index f37316d2c8fa..f9375b77d17d 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1196,15 +1196,6 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		/* FIXME: What new port features do we need to support? */
 		switch (wValue) {
 		case USB_PORT_FEAT_SUSPEND:
-			temp = readl(ports[wIndex]->addr);
-			if ((temp & PORT_PLS_MASK) != XDEV_U0) {
-				/* Resume the port to U0 first */
-				xhci_set_link_state(xhci, ports[wIndex],
-							XDEV_U0);
-				spin_unlock_irqrestore(&xhci->lock, flags);
-				msleep(10);
-				spin_lock_irqsave(&xhci->lock, flags);
-			}
 			/* In spec software should not attempt to suspend
 			 * a port unless the port reports that it is in the
 			 * enabled (PED = ‘1’,PLS < ‘3’) state.
@@ -1645,8 +1636,10 @@ int xhci_bus_suspend(struct usb_hcd *hcd)
 			xhci_dbg(xhci, "Bus suspend bailout, port over-current detected\n");
 			return -EBUSY;
 		}
-		/* suspend ports in U0, or bail out for new connect changes */
-		if ((t1 & PORT_PE) && (t1 & PORT_PLS_MASK) == XDEV_U0) {
+		/* suspend ports in U0/U1/U2, or bail out for new connect changes */
+		if ((t1 & PORT_PE) && ((t1 & PORT_PLS_MASK) == XDEV_U0 ||
+				       (t1 & PORT_PLS_MASK) == XDEV_U1 ||
+				       (t1 & PORT_PLS_MASK) == XDEV_U2)) {
 			if ((t1 & PORT_CSC) && wake_enabled) {
 				bus_state->bus_suspended = 0;
 				spin_unlock_irqrestore(&xhci->lock, flags);
-- 
2.17.1