Re: [PATCH v2] USB: Disable USB2 LPM at shutdown

[Kai-Heng Feng]

at 15:55, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:

> at 18:22, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
>
> > at 00:01, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
> >
> > > > On Jan 30, 2019, at 16:21, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > >
> > > > 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@xxxxxxxxxxxxx>
> > > > > ---
> > > > > 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.
> > >
> > > Yes I think this should be universally applied.
> > >
> > > I donât think the bug only happens to one device. Users wonât find this
> > > unless they connect their laptop to a power meter.
> > >
> > > Platform may not completely cut off USB bus power during shutdown,
> > > so the device transits to L1 after system shutdown. Now xHC is disabled
> > > so nothing can bring it back to L0 or L2.
> >
> > It would be great if someone can come up with better ideas.
> >
> > We can also use other approaches, but currently this is the only way I  
> > can think of.
>
> Alan and Mathias,
>
> It would be great if you can review this patch, or give me some suggestion.

Can I get some advice here?
I really think disabling LPM should be universally applied.

Kai-Heng

> Kai-Heng
>
> > Kai-Heng
> >
> > > Kai-Heng
> > >
> > > > thanks,
> > > >
> > > > greg k-h