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>

2 files changed, 56 insertions, 14 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);
 
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index d9ec2de6c4cf..65b6e6b84043 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -531,7 +531,7 @@ static ssize_t usb2_lpm_besl_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(usb2_lpm_besl);
 
-static ssize_t usb3_hardware_lpm_show(struct device *dev,
+static ssize_t usb3_hardware_lpm_u1_show(struct device *dev,
 				      struct device_attribute *attr, char *buf)
 {
 	struct usb_device *udev = to_usb_device(dev);
@@ -539,7 +539,7 @@ static ssize_t usb3_hardware_lpm_show(struct device *dev,
 
 	usb_lock_device(udev);
 
-	if (udev->usb3_lpm_enabled)
+	if (udev->usb3_lpm_u1_enabled)
 		p = "enabled";
 	else
 		p = "disabled";
@@ -548,7 +548,26 @@ static ssize_t usb3_hardware_lpm_show(struct device *dev,
 
 	return sprintf(buf, "%s\n", p);
 }
-static DEVICE_ATTR_RO(usb3_hardware_lpm);
+static DEVICE_ATTR_RO(usb3_hardware_lpm_u1);
+
+static ssize_t usb3_hardware_lpm_u2_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct usb_device *udev = to_usb_device(dev);
+	const char *p;
+
+	usb_lock_device(udev);
+
+	if (udev->usb3_lpm_u2_enabled)
+		p = "enabled";
+	else
+		p = "disabled";
+
+	usb_unlock_device(udev);
+
+	return sprintf(buf, "%s\n", p);
+}
+static DEVICE_ATTR_RO(usb3_hardware_lpm_u2);
 
 static struct attribute *usb2_hardware_lpm_attr[] = {
 	&dev_attr_usb2_hardware_lpm.attr,
@@ -562,7 +581,8 @@ static struct attribute_group usb2_hardware_lpm_attr_group = {
 };
 
 static struct attribute *usb3_hardware_lpm_attr[] = {
-	&dev_attr_usb3_hardware_lpm.attr,
+	&dev_attr_usb3_hardware_lpm_u1.attr,
+	&dev_attr_usb3_hardware_lpm_u2.attr,
 	NULL,
 };
 static struct attribute_group usb3_hardware_lpm_attr_group = {
@@ -592,7 +612,8 @@ static int add_power_attributes(struct device *dev)
 		if (udev->usb2_hw_lpm_capable == 1)
 			rc = sysfs_merge_group(&dev->kobj,
 					&usb2_hardware_lpm_attr_group);
-		if (udev->lpm_capable == 1)
+		if (udev->speed == USB_SPEED_SUPER &&
+				udev->lpm_capable == 1)
 			rc = sysfs_merge_group(&dev->kobj,
 					&usb3_hardware_lpm_attr_group);
 	}