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

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Date:   Mon, 3 Dec 2018 16:36:13 +0800
From:   Kai Heng Feng <kai.heng.feng@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linux USB List <linux-usb@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] USB: Don't enable LPM if it's already enabled



> On Dec 3, 2018, at 4:32 PM, Kai-Heng Feng <kai.heng.feng@...onical.com> 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.

Please ignore this patch, I missed Greg’s suggestion to use _enable() and _disable() naming.

Will send a v4.

Kai-Heng

> 
> 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
>