Re: [PATCH v6 5/5] mfd: max77541: Add ADI MAX77541/MAX77540 PMIC Support

[Nuno Sá]

On Tue, 2023-03-28 at 17:35 +0300, Andy Shevchenko wrote:
> On Tue, Mar 28, 2023 at 04:18:30PM +0200, Nuno Sá wrote:
> > On Tue, 2023-03-28 at 14:46 +0100, Mark Brown wrote:
> > > On Tue, Mar 28, 2023 at 03:26:44PM +0200, Nuno Sá wrote:
> > > 
> > > > IIRC, regmap_read() is not really reentrant and it is used in
> > > > the
> > > > IIO
> > > > driver on the sysfs interface. So, yeah, I think you need the
> > > > regmap
> > > > lock and better just leave the config as is. Yes, the lock is
> > > > opt-
> > > > out
> > > > so let's not disable it :)
> > > 
> > > All the regmap operations are fully thread safe.
> > 
> > Even if 'config->disable_locking' is set? I think that is what's
> > being
> > discussed in here...
> 
> In case the driver has its own lock to serialize IO how on earth the
> regmap
> lock is needed. That's what I asked the author of the driver. He told
> the code

Well, if the driver has it's own locking, then sure we do not need
regmap's lock...

> doesn't require the regmap lock, and I tend to believe the author.
> So, why to
> keep it?
> 

However, if you look at the adc driver, I can see plain regmap_read()
calls without any "outside" locking.

- Nuno Sá