[PATCH 5/9] ARM: dove: create a proper PMU driver for power domains, PMU IRQs and resets

Russell King - ARM Linux linux at arm.linux.org.uk
Fri Mar 13 05:47:48 PDT 2015

On Fri, Mar 13, 2015 at 01:42:35PM +0100, Arnd Bergmann wrote:
> On Friday 13 March 2015 12:29:44 Russell King - ARM Linux wrote:
> > The hardware requires a specific sequence of register writes for the
> > PM domain code, which includes the reset register.
> > 
> > The problem is that if we were to use the reset API directly from the
> > PM domain code, we would have to separate the locks for the reset code
> > from the PM domain code.  That then leads to there being a race between
> > the reset code potentially being able to write to the reset register in
> > the middle of a PM domain sequence.
> I see. I may be missing something here, but I think you could still
> use of_reset_controller_get() once the reset controller is enabled
> and then manually access the register from the PM domain code while
> holding the pmu lock. You wouldn't be able to use device_reset()
> or similar as you explain, but you could avoid parsing the DT manually.

What about the case when CONFIG_RESET_CONTROLLER is disabled?  In that
case, I would then need to manually parse this anyway.

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