Re: [PATCH v2] i2c: sh_mobile: implement atomic transfers

[Wolfram Sang <wsa@the-dreams.de>]

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Hi Geert,

I spend some more thoughts on this.

> > > In general, pm_runtime_get_sync() is not safe to call from atomic
> > > context.
> > > For Renesas SoCs, I think both the power and clock domains are safe, as
> > > the respective drivers don't sleep.  The PM core might, though.
> >
> > Still, that sounds to me like we should protect these calls as in V1?

I still think we should guard these calls just because it is not safe to
call them from atomic contexts.

> And talk to the i2c controller while it is disabled?

Is there maybe some "always-on" property which we could add to the
respective IIC clock?

> That does seem to work on R-Car Gen2 (similar to SMP bringup accessing
> registers of a disabled WDT?), though.

Yes. Uli's patch will not cause a regression because we are already
calling i2c_transfer very late. And we do call the runtime_pm functions
currently. So, it will improve the situation there.

> Needs testing on R-Mobile A1....

That's armadillo, right? I don't have that, sadly.

Thanks,

   Wolfram


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