usb: core: lpm: fix usb3_hardware_lpm sysfs node

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 30 insertions, 9 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bdeadc112d29..59f998e60030 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,30 @@ static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
 		return;
 	}
 
-	if (usb_set_lpm_timeout(udev, state, timeout))
+	if (usb_set_lpm_timeout(udev, state, timeout)) {
 		/* If we can't set the parent hub U1/U2 timeout,
 		 * device-initiated LPM won't be allowed either, so let the xHCI
 		 * host know that this link state won't be enabled.
 		 */
 		hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
+	} else {
+		/* Only a configured device will accept the Set Feature
+		 * U1/U2_ENABLE
+		 */
+		if (udev->actconfig)
+			usb_set_device_initiated_lpm(udev, state, true);
 
-	/* Only a configured device will accept the Set Feature U1/U2_ENABLE */
-	else if (udev->actconfig)
-		usb_set_device_initiated_lpm(udev, state, true);
-
+		/* As soon as usb_set_lpm_timeout(timeout) returns 0, the
+		 * hub-initiated LPM is enabled. Thus, LPM is enabled no
+		 * matter the result of usb_set_device_initiated_lpm().
+		 * The only difference is whether device is able to initiate
+		 * LPM.
+		 */
+		if (state == USB3_LPM_U1)
+			udev->usb3_lpm_u1_enabled = 1;
+		else if (state == USB3_LPM_U2)
+			udev->usb3_lpm_u2_enabled = 1;
+	}
 }
 
 /*
@@ -3925,6 +3938,18 @@ static int usb_disable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
 		dev_warn(&udev->dev, "Could not disable xHCI %s timeout, "
 				"bus schedule bandwidth may be impacted.\n",
 				usb3_lpm_names[state]);
+
+	/* As soon as usb_set_lpm_timeout(0) return 0, hub initiated LPM
+	 * is disabled. Hub will disallows link to enter U1/U2 as well,
+	 * even device is initiating LPM. Hence LPM is disabled if hub LPM
+	 * timeout set to 0, no matter device-initiated LPM is disabled or
+	 * not.
+	 */
+	if (state == USB3_LPM_U1)
+		udev->usb3_lpm_u1_enabled = 0;
+	else if (state == USB3_LPM_U2)
+		udev->usb3_lpm_u2_enabled = 0;
+
 	return 0;
 }
 
@@ -3959,8 +3984,6 @@ int usb_disable_lpm(struct usb_device *udev)
 	if (usb_disable_link_state(hcd, udev, USB3_LPM_U2))
 		goto enable_lpm;
 
-	udev->usb3_lpm_enabled = 0;
-
 	return 0;
 
 enable_lpm:
@@ -4018,8 +4041,6 @@ void usb_enable_lpm(struct usb_device *udev)
 
 	usb_enable_link_state(hcd, udev, USB3_LPM_U1);
 	usb_enable_link_state(hcd, udev, USB3_LPM_U2);
-
-	udev->usb3_lpm_enabled = 1;
 }
 EXPORT_SYMBOL_GPL(usb_enable_lpm);