Re: [PATCH] Fix clk->enabled counter

[David Brownell <david-b@xxxxxxxxxxx>]

On Saturday 19 January 2008, Dmitry Baryshkov wrote:
> > Minor issues as noted below.  You tested this?  With suspend, resume,
> > remote wakeup, unplug-while-active, and rmmod g_<what> scenarios to make
> > sure the main code paths behave OK?
> 
> I've tested with g_ether the suspend/resume of gadget (got log messages
> as found bellow, but otherwise OK),

Hmm, looks like you were testing system suspend/resume (initiated
by writing to /sys/power/state) when that lockdep problem showed up,
not USB suspend/resume (initiated by the host).  Actually *BOTH* of
those sequences need to be tested!

The lockdep warning should go away.  It's basically saying that
this code predates lockdep, and has an associated bug.  The bug
fix looks to be along the lines of ensuring that IRQs are blocked
during pxa2xx_udc_{suspend,resume}() methods ... the easiest way
to fix that is updating the udc_driver struct to make those become
the late_suspend and early_resume methods, which are always called
with IRQs disabled (so you won't need to do it yourself).

(And kudos on running -- or at least testing! -- with lockdep.
That's a practice all developers should follow, and too few of
them do so.)


> plug-unplug also works. Can't test 
> rmmod/modrobe as I don't build modular kernels for my device.

Well, if you can't do that then you can't.  The trick is rmmod
while the device is active.  That can be problematic, since it
forces a clean shutdown in a different way than disconnect.


> Also what do you mean by remote wakeup?

See the USB 2.0 spec for definition.  The easy way to test it is
as described in http://www.linux-usb.org/usbtest where it says how
to set up g_zero with "autoresume=5" to ensure the remote wakeup
tests can run with USBCV.  There are no easy automated tests to
run on Linux.

In fact, running USBCV is also the easiest way to test USB suspend
and resume too.


> I'll try making modules to work, fix things you noted and resubmit the patch.

Thanks.  It basically looks OK, but that's code I've learned to
be cautious with.  It's easy for subtle bugs to creep in ... as
you may have deduced by noticing that lockdep bug.

- Dave
 



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