Re: [PATCH v4 01/13] USB: ch341: fix error handling on resume

Johan Hovold
2016-05-02T13:45:52Z

On Fri, Apr 29, 2016 at 05:11:13PM +0200, Grigori Goronzy wrote:
> On 2016-04-29 14:16, Johan Hovold wrote:
> > On Fri, Apr 15, 2016 at 11:14:04PM +0200, Grigori Goronzy wrote:
> >> This may fail, do not assume it always works.
> >>
> >> Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
> >> ---
> >> drivers/usb/serial/ch341.c | 4 +---
> >> 1 file changed, 1 insertion(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
> >> index c73808f..63df8ce 100644
> >> --- a/drivers/usb/serial/ch341.c
> >> +++ b/drivers/usb/serial/ch341.c
> >> @@ -544,9 +544,7 @@ static int ch341_reset_resume(struct usb_serial
> >> *serial)
> >> priv = usb_get_serial_port_data(serial->port[0]);
> >>
> >> /* reconfigure ch341 serial port after bus-reset */
> >> - ch341_configure(serial->dev, priv);
> >> -
> >> - return 0;
> >> + return ch341_configure(serial->dev, priv);
> >
> > This is correct, but have noticed that resume is currently broken in
> > that the interrupt urb is never resubmitted on resume in case the port
> > is
> > already open?
> >
> > Also ch341_configure must not use GFP_KERNEL either if called from a
> > resume path (use GFP_NOIO).
> >
> > Care to fix this up as well?
> >
>
> Sure. How can I trigger a reset properly? AFAIR, I tried USBDEVFS_RESET
> and it didn't really do what I wanted, at least the reset_resume
> callback wasn't invoked.

You should be able to use the USB persistent-device functionality or
temporarily enable the USB_QUIRK_RESET_RESUME quirk for your device to
have reset_resume be called on system resume, but note that a resume
callback also needs to be implemented for normal (system and runtime)
resume.

Also note that reset_resume for usb-serial is currently broken in
mainline (since 4.5).

Thanks,
Johan