Re: [PATCH v2 0/4] gpio: fix an incorrect lockdep warning

From: Wolfram Sang
Date: Sat Sep 17 2016 - 06:19:21 EST

On Sat, Sep 17, 2016 at 03:19:52AM +0200, Peter Zijlstra wrote:
> On Fri, Sep 16, 2016 at 06:02:41PM +0200, Bartosz Golaszewski wrote:
> > If an I2C GPIO multiplexer is driven by a GPIO provided by an expander
> > when there's a second expander using the same device driver on one of
> > the I2C bus segments, lockdep prints a deadlock warning when trying to
> > set the direction or the value of the GPIOs provided by the second
> > expander.
> >
> > This series exports an already existing function from i2c-core as
> > public API and reuses it in pca953x to pass a correct lock subclass
> > to lockdep.
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Oops, I overlooked that I need your ack as well :) Thanks!

> > Note: if this series gets merged, I'll prepare follow-up patches for
> > other expanders for which a similar problem could potentially occur.
> We can't push this annotation into the i2c core, can we? Since the mutex
> is in driver specific code, not more generic...

Afraid so.

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