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SubjectRe: [PATCH v2] USB: Disable USB2 LPM at shutdown
On Thu, Jan 24, 2019 at 02:16:43PM +0800, Kai-Heng Feng 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.
>
> Disable LPM at shutdown to 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@canonical.com>
> ---
> v2: Use new LPM helpers.
>
> drivers/usb/core/port.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
> index 1a06a4b5fbb1..bbbb35fa639f 100644
> --- a/drivers/usb/core/port.c
> +++ b/drivers/usb/core/port.c
> @@ -285,6 +285,14 @@ 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_disable_usb2_hardware_lpm(port_dev->child);
> +}
> +
> static const struct dev_pm_ops usb_port_pm_ops = {
> #ifdef CONFIG_PM
> .runtime_suspend = usb_port_runtime_suspend,
> @@ -301,6 +309,7 @@ struct device_type usb_port_device_type = {
> static struct device_driver usb_port_driver = {
> .name = "usb",
> .owner = THIS_MODULE,
> + .shutdown = usb_port_shutdown,
> };

So you now do this for all ports in the system, no matter what is
plugged in or not. Are you _SURE_ you want to do that? It seems like a
big hammer to solve just one single device's problems.

thanks,

greg k-h

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