Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux controller

From	Philipp Zabel <p.zabel@pengutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux controller
Date	2017-04-21 19:10 +0200
Message-ID	<tyKee-8vc-33@gated-at.bofh.it> (permalink)
References	<txwQ2-3Wq-21@gated-at.bofh.it> <txwQ2-3Wq-23@gated-at.bofh.it> <tyHJo-6SD-37@gated-at.bofh.it> <tyKee-8vc-31@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Fri, 2017-04-21 at 16:32 +0200, Peter Rosin wrote:
> On 2017-04-21 16:23, Philipp Zabel wrote:
> > On Thu, 2017-04-13 at 18:43 +0200, Peter Rosin wrote:
> > [...]
> >> +int mux_chip_register(struct mux_chip *mux_chip)
> >> +{
> >> +	int i;
> >> +	int ret;
> >> +
> >> +	for (i = 0; i < mux_chip->controllers; ++i) {
> >> +		struct mux_control *mux = &mux_chip->mux[i];
> >> +
> >> +		if (mux->idle_state == mux->cached_state)
> >> +			continue;
> > 
> > I think this should be changed to
> >  
> > -               if (mux->idle_state == mux->cached_state)
> > +               if (mux->idle_state == mux->cached_state ||
> > +                   mux->idle_state == MUX_IDLE_AS_IS)
> >                         continue;
> > 
> > or the following mux_control_set will be called with state ==
> > MUX_IDLE_AS_IS. Alternatively, mux_control_set should return when passed
> > this value.
> 
> That cannot happen because ->cached_state is initialized to -1
> in mux_chip_alloc, so should always be == MUX_IDLE_AS_IS when
> registering. And drivers are not supposed to touch ->cached_state.
> I.e., ->cached_state is "owned" by the core.

So this was caused by me filling cached_state from register reads in the
mmio driver. Makes me wonder why I am not allowed to do this, though, if
I am able to read back the initial state?

regards
Philipp

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux  controller Philipp Zabel <p.zabel@pengutronix.de> - 2017-04-21 16:30 +0200
  Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux  controller Philipp Zabel <p.zabel@pengutronix.de> - 2017-04-21 19:10 +0200
  Re: [PATCH v13 03/10] mux: minimal mux subsystem and gpio-based mux  controller Philipp Zabel <p.zabel@pengutronix.de> - 2017-04-21 19:10 +0200

csiph-web