Re: [PATCH v4] USB: Don't enable LPM if it's already enabled

[Kai Heng Feng]

Hi,

> On Dec 3, 2018, at 18:26, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
> 
> 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().

Please review my new approach, hopefully this can be included in Linux v5.0. 

> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> ---
> 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
>