linux-kernel - Re: [PATCH] USB: Disable USB2 LPM at shutdown

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Message-Id: <EDF7D3E0-D82D-436E-9F31-45D440A103FE@canonical.com>
Date:   Fri, 23 Nov 2018 14:04:45 +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] USB: Disable USB2 LPM at shutdown

Hi,

> On Nov 7, 2018, at 1:34 AM, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
> 
> The QCA Rome USB Bluetooth controller has several issues once LPM gets
> enabled:
> - Fails to get enumerated in coldboot. [1]
> - Drains more power (~ 0.2W) when the system is in S5. [2]
> - Disappears after a warmboot. [2]
> 
> The issue happens because the device lingers at LPM L1 in S5, so device
> can't get enumerated even after a reboot.
> 
> Disalbe LPM at shutdown can solve the issue.
> 
> [1] https://bugs.launchpad.net/bugs/1757218
> [2] https://patchwork.kernel.org/patch/10607097/
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>

Would it be possible to merge this patch?

Kai-Heng

> ---
> drivers/usb/core/port.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
> index 1a06a4b5fbb1..15f6924a4d84 100644
> --- a/drivers/usb/core/port.c
> +++ b/drivers/usb/core/port.c
> @@ -285,6 +285,15 @@ static int usb_port_runtime_suspend(struct device *dev)
> }
> #endif
> 
> +static void usb_port_shutdown(struct device *dev)
> +{
> +	struct usb_port *port_dev = to_usb_port(dev);
> +
> +	if (port_dev->child)
> +		usb_set_usb2_hardware_lpm(port_dev->child, 0);
> +
> +}
> +
> static const struct dev_pm_ops usb_port_pm_ops = {
> #ifdef CONFIG_PM
> 	.runtime_suspend =	usb_port_runtime_suspend,
> @@ -301,6 +310,7 @@ struct device_type usb_port_device_type = {
> static struct device_driver usb_port_driver = {
> 	.name = "usb",
> 	.owner = THIS_MODULE,
> +	.shutdown = usb_port_shutdown,
> };
> 
> static int link_peers(struct usb_port *left, struct usb_port *right)
> -- 
> 2.19.1
>