On Fri, Feb 8, 2019 at 9:55 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > > On 08-02-19, 09:12, Marek Szyprowski wrote: > > On 2019-02-08 07:49, Viresh Kumar wrote: > > > Why don't you get similar problem during suspend? I think you can get > > > it when the CPUs are offlined as I2C would have gone by then. The > > > cpufreq or OPP core can try and run some regulator or genpd or clk > > > calls to disable resources, etc. Even if doesn't happen, it certainly > > > can. > > > > CPUfreq is suspended very early during system suspend and thus it does > > nothing when CPUs are being offlined. > > > > Also at resume the cpufreq core may try to change the frequency right > > > from ->init() on certain cases, though not everytime and so the > > > problem can come despite of this series. > > > > cpufreq is still in suspended state (it is being 'resume' very late in > > the system resume procedure), so if driver doesn't explicitly change any > > opp in ->init(), then cpufreq core waits until everything is resumed. To > > sum up, this seems to be fine, beside the issue with regulator > > initialization I've addressed in this patchset. > > Yeah, the governors are suspended very soon, but any frequency change > starting from cpufreq core can still happen. There are at least two > points in cpufreq_online() where we may end up changing the frequency, > but that is conditional and may not be getting hit. > > > > We guarantee that the resources are available during probe but not > > > during resume, that's where the problem is. > > > > Yes, so I've changed cpufreq-dt to the common approach, in which the > > driver keeps all needed resources for the whole lifetime of the device. > > That's not what I was saying actually. I was saying that it should be > fine to do a I2C transfer during resume, Surely not before resuming the I2C controller involved? > else we will always have > problems and have to fix them with hacks like the one you proposed > where you acquire resources for all the possible CPUs. Maybe we can > fix it once and for all. Obviously, all I2C transfers need to take place either before suspending the I2C controller or after resuming it.
