On Tue, 30 Oct 2018, Mathias Nyman wrote:
> On 30.10.2018 07:54, Kai-Heng Feng 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.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > ---
> > drivers/usb/core/driver.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> > index 53564386ed57..e11d2eac76b6 100644
> > --- a/drivers/usb/core/driver.c
> > +++ b/drivers/usb/core/driver.c
> > @@ -1901,7 +1901,8 @@ 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 (enable && !udev->usb2_hw_lpm_allowed ||
> > + udev->usb2_hw_lpm_enabled == enable)
> > return 0;
> >
> > if (hcd->driver->set_usb2_hw_lpm) {
> >
>
> Something like that would probably work.
>
> Would it make sense to skip USB2 hw LPM enabling in usb_port_resume() if
> port was just reset (and thus LPM enabled)?
>
> something like this:
>
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -3520,7 +3520,7 @@ 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)
> + if (udev->usb2_hw_lpm_capable == 1 && !udev->reset_resume)
> usb_set_usb2_hardware_lpm(udev, 1);
>
> /* Try to enable USB3 LTM */
Why not simply test whether udev->usb2_hw_lpm_enabled is already true?
if (udev->usb2_hw_lpm_capable == 1 &&
!udev->usb2_hw_lpm_enabled)
Or even put this extra test into usb_set_usb2_hardware_lpm().
Alan Stern
