On Fri, Feb 8, 2019 at 1:04 PM Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > > Hi Sudeep, > > On 2019-02-08 12:51, Sudeep Holla wrote: > > On Fri, Feb 08, 2019 at 12:47:06PM +0100, Marek Szyprowski wrote: > >> 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. > > Frankly, I don't feel I know enough to touch this driver and I don't > think that this can even be fixed in a generic way in the cpufreq core. > Maybe a comment somewhere is needed that ->init() might be called during > early system resume with irqs off and driver is responsible for handling > such case until the proper resume? Well, adding a comment to that effect certainly won't hurt as that's how things work now. However, it looks like something needs to be done in addition to that.
