linux-kernel - [PATCH v3] USB: Don't enable LPM if it's already enabled

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Date:   Mon,  3 Dec 2018 16:32:08 +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 v3] 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.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
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  |  4 +++-
 drivers/usb/core/hub.c     | 13 ++++---------
 drivers/usb/core/message.c |  3 +--
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 53564386ed57..f277a8de7498 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1901,7 +1901,9 @@ 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)
+	if (!udev->usb2_hw_lpm_capable ||
+	    (enable && !udev->usb2_hw_lpm_allowed) ||
+	    (enable && udev->usb2_hw_lpm_enabled))
 		return 0;
 
 	if (hcd->driver->set_usb2_hw_lpm) {
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index e482e5f103d9..907793d38a82 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_set_usb2_hardware_lpm(udev, 0);
 
 	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_set_usb2_hardware_lpm(udev, 1);
 
 		if (udev->do_remote_wakeup)
 			(void) usb_disable_remote_wakeup(udev);
@@ -3533,9 +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 &&
-		    !udev->usb2_hw_lpm_enabled)
-			usb_set_usb2_hardware_lpm(udev, 1);
+		usb_set_usb2_hardware_lpm(udev, 1);
 
 		/* Try to enable USB3 LTM */
 		usb_enable_ltm(udev);
@@ -5639,8 +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_set_usb2_hardware_lpm(udev, 0);
 
 	/* Disable LPM while we reset the device and reinstall the alt settings.
 	 * Device-initiated LPM, and system exit latency settings are cleared
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index bfa5eda0cc26..a00952bdf645 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_set_usb2_hardware_lpm(dev, 0);
 		usb_unlocked_disable_lpm(dev);
 		usb_disable_ltm(dev);
 
-- 
2.17.1