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? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
