Re: question about usb_rebind_intf

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Nov 17, 2017 at 01:21:28PM -0500, Alan Stern wrote:
> On Fri, 17 Nov 2017, Mathias Nyman wrote:
> 
> > On 17.11.2017 19:09, Greg Kroah-Hartman wrote:
> > > On Fri, Nov 17, 2017 at 09:35:51AM -0700, Jerry Snitselaar wrote:
> > >> Should this skip warning that the rebind failed if device_attach
> > >> is returning -EPROBE_DEFER? If I do something like 'rtcwake -m mem -s 30'
> > >> on a laptop I have here I will see a couple "rebind failed: -517" messages
> > >> as it comes back out of suspend. Since the device probe eventually happens
> > >> once probes are not deferred wondering if this warning this be given in that
> > >> case.
> > >>
> > >>
> > >> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> > >> index 64262a9a8829..5d3408010112 100644
> > >> --- a/drivers/usb/core/driver.c
> > >> +++ b/drivers/usb/core/driver.c
> > >> @@ -1070,7 +1070,7 @@ static void usb_rebind_intf(struct usb_interface *intf)
> > >>         if (!intf->dev.power.is_prepared) {
> > >>                 intf->needs_binding = 0;
> > >>                 rc = device_attach(&intf->dev);
> > >> -               if (rc < 0)
> > >> +               if (rc < 0 && rc != -EPROBE_DEFER)
> > >>                         dev_warn(&intf->dev, "rebind failed: %d\n", rc);
> > >>         }
> > >> }
> > > 
> > > What USB driver is returning -EPROBE_DEFER to cause this to be an issue?
> > > Shouldn't that really only be for "platform" drivers and the like?  USB
> > > interface drivers should all be "self-contained" within reason.
> > > 
> > 
> > I see this as well with btusb driver in resume if port was reset.
> > 
> > drivers/base/dd.c really_probe() returns -EPROBE_DEFER if it's called before
> > device_unblock_probing() is called.
> > 
> > drivers/base/power/main/dpm_complete() will unlock probing after it has
> > finished resuming all devices and called all the pm_ops .complete callbacks.
> > 
> > The usb_device_pm_ops .complete callback will try to rebind the interface driver
> > if device was reset at resume, leading to them -EPROBE_DEFER.
> >   
> > I guess we either need to rework a few things, or remove that warning.
> 
> I agree, and the patch seems like a good idea for now.

Ah, I forgot about the reset stuff.

If someone sends this patch in a format that can be applied, that would
be nice :)

thanks,

greg k-h