Date:   Mon,  3 Dec 2018 18:26:43 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH v4] USB: Don't enable LPM if it's already enabled

USB Bluetooth controller QCA ROME (0cf3:e007) sometimes stops working
after S3:
[ 165.110742] Bluetooth: hci0: using NVM file: qca/nvm_usb_00000302.bin
[ 168.432065] Bluetooth: hci0: Failed to send body at 4 of 1953 (-110)

After some experiments, I found that disabling LPM can workaround the
issue.

On some platforms, the USB power is cut during S3, so the driver uses
reset-resume to resume the device. During port resume, LPM gets enabled
twice, by usb_reset_and_verify_device() and usb_port_resume().

So let's enable LPM for just once, as this solves the issue for the
device in question.

Also consolidate USB2 LPM functions to usb_enable_usb2_hardware_lpm()
and usb_disable_usb2_hardware_lpm().

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v4:
 - Use usb_enable_usb2_hardware_lpm() and
   usb_disable_usb2_hardware_lpm() to control USB2 LPM.
v3:
 - Consolidate udev->usb2_hw_lpm_capable and udev->usb2_hw_lpm_enabled
  check to usb_set_usb2_hardware_lpm().
v2:
  - Check udev->usb2_hw_lpm_enabled before calling usb_port_resume().

 drivers/usb/core/driver.c  | 23 +++++++++++++++++++----
 drivers/usb/core/hub.c     | 16 ++++++----------
 drivers/usb/core/message.c |  3 +--
 drivers/usb/core/sysfs.c   |  5 ++++-
 drivers/usb/core/usb.h     | 10 ++++++++--
 5 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 53564386ed57..8987cec9549d 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1896,14 +1896,11 @@ int usb_runtime_idle(struct device *dev)
 	return -EBUSY;
 }
 
-int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
+static int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
 {
 	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
 	int ret = -EPERM;
 
-	if (enable && !udev->usb2_hw_lpm_allowed)
-		return 0;
-
 	if (hcd->driver->set_usb2_hw_lpm) {
 		ret = hcd->driver->set_usb2_hw_lpm(hcd, udev, enable);
 		if (!ret)
@@ -1913,6 +1910,24 @@ int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
 	return ret;
 }
 
+int usb_enable_usb2_hardware_lpm(struct usb_device *udev)
+{
+	if (!udev->usb2_hw_lpm_capable ||
+	    !udev->usb2_hw_lpm_allowed ||
+	    udev->usb2_hw_lpm_enabled)
+		return 0;
+
+	return usb_set_usb2_hardware_lpm(udev, 1);
+}
+
+int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
+{
+	if (!udev->usb2_hw_lpm_enabled)
+		return 0;
+
+	return usb_set_usb2_hardware_lpm(udev, 0);
+}
+
 #endif /* CONFIG_PM */
 
 struct bus_type usb_bus_type = {
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 0f9381b69a3b..b4439ee2d144 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3210,8 +3210,7 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 	}
 
 	/* disable USB2 hardware LPM */
-	if (udev->usb2_hw_lpm_enabled == 1)
-		usb_set_usb2_hardware_lpm(udev, 0);
+	usb_disable_usb2_hardware_lpm(udev);
 
 	if (usb_disable_ltm(udev)) {
 		dev_err(&udev->dev, "Failed to disable LTM before suspend\n");
@@ -3249,8 +3248,7 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 		usb_enable_ltm(udev);
  err_ltm:
 		/* Try to enable USB2 hardware LPM again */
-		if (udev->usb2_hw_lpm_capable == 1)
-			usb_set_usb2_hardware_lpm(udev, 1);
+		usb_enable_usb2_hardware_lpm(udev);
 
 		if (udev->do_remote_wakeup)
 			(void) usb_disable_remote_wakeup(udev);
@@ -3533,8 +3531,7 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
 		hub_port_logical_disconnect(hub, port1);
 	} else  {
 		/* Try to enable USB2 hardware LPM */
-		if (udev->usb2_hw_lpm_capable == 1)
-			usb_set_usb2_hardware_lpm(udev, 1);
+		usb_enable_usb2_hardware_lpm(udev);
 
 		/* Try to enable USB3 LTM */
 		usb_enable_ltm(udev);
@@ -4425,7 +4422,7 @@ static void hub_set_initial_usb2_lpm_policy(struct usb_device *udev)
 	if ((udev->bos->ext_cap->bmAttributes & cpu_to_le32(USB_BESL_SUPPORT)) ||
 			connect_type == USB_PORT_CONNECT_TYPE_HARD_WIRED) {
 		udev->usb2_hw_lpm_allowed = 1;
-		usb_set_usb2_hardware_lpm(udev, 1);
+		usb_enable_usb2_hardware_lpm(udev);
 	}
 }
 
@@ -5638,8 +5635,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 	/* Disable USB2 hardware LPM.
 	 * It will be re-enabled by the enumeration process.
 	 */
-	if (udev->usb2_hw_lpm_enabled == 1)
-		usb_set_usb2_hardware_lpm(udev, 0);
+	usb_disable_usb2_hardware_lpm(udev);
 
 	/* Disable LPM while we reset the device and reinstall the alt settings.
 	 * Device-initiated LPM, and system exit latency settings are cleared
@@ -5742,7 +5738,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 
 done:
 	/* Now that the alt settings are re-installed, enable LTM and LPM. */
-	usb_set_usb2_hardware_lpm(udev, 1);
+	usb_enable_usb2_hardware_lpm(udev);
 	usb_unlocked_enable_lpm(udev);
 	usb_enable_ltm(udev);
 	usb_release_bos_descriptor(udev);
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index bfa5eda0cc26..4f33eb632a88 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1243,8 +1243,7 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
 			dev->actconfig->interface[i] = NULL;
 		}
 
-		if (dev->usb2_hw_lpm_enabled == 1)
-			usb_set_usb2_hardware_lpm(dev, 0);
+		usb_disable_usb2_hardware_lpm(dev);
 		usb_unlocked_disable_lpm(dev);
 		usb_disable_ltm(dev);
 
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index ea18284dfa9a..7e88fdfe3cf5 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -528,7 +528,10 @@ static ssize_t usb2_hardware_lpm_store(struct device *dev,
 
 	if (!ret) {
 		udev->usb2_hw_lpm_allowed = value;
-		ret = usb_set_usb2_hardware_lpm(udev, value);
+		if (value)
+			ret = usb_enable_usb2_hardware_lpm(udev);
+		else
+			ret = usb_disable_usb2_hardware_lpm(udev);
 	}
 
 	usb_unlock_device(udev);
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index 546a2219454b..d95a5358f73d 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -92,7 +92,8 @@ extern int usb_remote_wakeup(struct usb_device *dev);
 extern int usb_runtime_suspend(struct device *dev);
 extern int usb_runtime_resume(struct device *dev);
 extern int usb_runtime_idle(struct device *dev);
-extern int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable);
+extern int usb_enable_usb2_hardware_lpm(struct usb_device *udev);
+extern int usb_disable_usb2_hardware_lpm(struct usb_device *udev);
 
 #else
 
@@ -112,7 +113,12 @@ static inline int usb_autoresume_device(struct usb_device *udev)
 	return 0;
 }
 
-static inline int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
+static inline int usb_enable_usb2_hardware_lpm(struct usb_device *udev)
+{
+	return 0;
+}
+
+static inline int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
 {
 	return 0;
 }
-- 
2.17.1

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