On Mon, Sep 02, 2013 at 11:07:35AM +0530, Pratyush Anand wrote:
> On Fri, Aug 30, 2013 at 02:58:25AM +0800, Alan Stern wrote:
> > On Thu, 29 Aug 2013, Sarah Sharp wrote:
> >
> > > On Thu, Aug 29, 2013 at 10:06:16AM -0700, Greg Kroah-Hartman wrote:
> > > > Hi Sarah,
> > > >
> > > > I'm getting the following warnings from the 3.10.9 kernel all the time
> > > > when I unplug a USB 3 storage device from my laptop:
> > > > [203282.987687] usb 4-1: USB disconnect, device number 21
> > > > [203282.992904] usb 4-1: Set SEL for device-initiated U1 failed.
> > > > [203282.992909] usb 4-1: Set SEL for device-initiated U2 failed.
> > > >
> > > > What can a "normal" user do with these "failed" messages? If nothing,
> > > > shouldn't we just turn them into debug messages instead?
> > >
> > > Yes, those messages should probably be toned down to debug level instead
> > > of warning level. If a device doesn't respond to the Set SEL request
> > > when USB 3.0 LPM is enabled, the user has a buggy device. Of course, I
> > > doubt anyone is going to return a drive based on those messages.
> > >
> > > That error message happens because the USB core is attempting to disable
>
> disable LPM or in case of enable LPM? Is n't this warning message
> coming from usb_enable_lpm -> usb_enable_link_state
>
> 3600 ret = usb_req_set_sel(udev, state);
> 3601 if (ret < 0) {
> 3602 dev_warn(&udev->dev, "Set SEL for
> device-initiated %s failed.\n",
> 3603 usb3_lpm_names[state]);
> 3604 return;
> 3605 }
You're right, but the USB core calling that function feels odd. Why
would we be *enabling* LPM for a device that's being disconnected?
Perhaps because the driver is being unbound from the device, the LPM ref
count drops to zero, we enable LPM, and then disable it as the device
disconnect continues?
Sarah Sharp
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