On Sun, 4 Apr 2010, Dominik Brodowski wrote:
> Alan, Oliver,
>
> On Sun, Apr 04, 2010 at 07:42:33PM +0200, Dominik Brodowski wrote:
> > Oliver,
> >
> > Unfortunately, autosuspend of btusb does not seem to work on my notebook
> > with 2.6.34-rc3:
>
> Debugging this a bit further (that's what long train rides are for):
>
> 1) btusb_open() gets called, which contains a pair of
> usb_autopm_get_interface(), usb_autopm_put_interface() calls. It
> sets needs_remote_wakeup = 1; in between there are two calls to
> usb_mark_last_busy().
>
> 2) There follow a few usb_mark_last_busy() calls.
>
> 3) Then, btusb_close() gets called, which again contains a pair of
> usb_autopm_{get,put}_interface() calls. Once btusb_close() returns,
> atomic_read(&intf->dev.power.usage_count) returns 0.
>
> This means that after startup, this usage_count is 0. Nonetheless,
> btusb's suspend callback is never called, despite the following settings:
>
> # cat /sys/module/usbcore/parameters/autosuspend
> 2
>
> # cat /sys/bus/usb/devices/7-1/power/level
> auto
The logic for autosuspend is more or less contained in
drivers/usb/core/driver.c:autosuspend_check(). It gets called from
usb_autopm_do_interface(), called by usb_autopm_put_interface().
(That's in 2.6.33; in 2.6.34-rc the arrangement is a little different
but not too much.) If you add some debugging statements to those
routines you ought to be able to figure out what's going on.
Alan Stern
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