Re: [PATCH 0/2] cpufreq/opp: rework regulator initialization

Sudeep Holla
2019-02-08T11:51:22Z

On Fri, Feb 08, 2019 at 12:47:06PM +0100, Marek Szyprowski wrote:
> Hi Sudeep,
>
> On 2019-02-08 12:00, Sudeep Holla wrote:
> > On Thu, Feb 07, 2019 at 01:22:25PM +0100, Marek Szyprowski wrote:
> >> Dear All,
> >>
> >> This is a scenario that triggers the above issue:
> > [...]
> >> 1. system disables non-boot cpu's at the end of system suspend procedure,
> >> 2. this in turn deinitializes cpufreq drivers for the disabled cpus,
> >> 3. early in the system resume procedure all cpus are got back to online
> >> state,
> >> 4. this in turn causes cpufreq to be initialized for the newly onlined
> >> cpus,
> >> 5. cpufreq-dt acquires all its resources (clocks, regulators) during
> >> ->init() callback,
> > This is strictly not just restricted to cpufreq-dt, but to any driver
> > supporting multiple policies. So we need a generic fix not just
> > cpufreq-dt specific.
>
> Could you point which other driver needs similar fix? Here in cpufreq-dt
> the problem was caused by using regulator api (indirectly) from
> ->init(). All other drivers, which have regulators support, are for old,
> obsolete, uni-processor systems, which don't have the problem of
> secondary cpu suspend during system suspend/resume cycle.
>

scmi_cpufreq for instance. We can fix that in driver my moving to polling
to get cpufreq_get_rate, but we support both polling and interrupt based.
We may wait for remote processor interrupt in get_rate.

--
Regards,
Sudeep