Hi Kevin, On Fri, Nov 30, 2018 at 12:28 AM Kevin Hilman <khil...@baylibre.com> wrote: > > Martin Blumenstingl <martin.blumensti...@googlemail.com> writes: > > > Hi Kevin, > > > > On Thu, Nov 29, 2018 at 1:30 AM Kevin Hilman <khil...@baylibre.com> wrote: > >> > >> Martin Blumenstingl <martin.blumensti...@googlemail.com> writes: > >> > >> > Some Meson8b boards (Odroid-C1, EC-100) use a PWM regulator which is the > >> > voltage supply of the CPU cores (this regulator is typically called > >> > "VCCK"). > >> > Now that we are preparing support for CPU frequency scaling on Meson8, > >> > Meson8b and Meson8m2 we should build the pwm-meson driver into the > >> > kernel so we can configure the CPU voltage early in the boot process. > >> > >> Can you explain a little more why the configuration of CPU voltage > >> cannot wait a bit so this could be properly probed? > > > > I was under the impression that cpufreq-dt would still initialize even > > if the regulator is not ready yet. however (after reading the code > > again) this is clearly NOT the case. > > Hmm, a quick look at cpufreq-dt suggests that it should -EPROBE_DEFER if > the regulator isn't ready yet. Why doesn't that work? sorry for not being clear: I was under the impression that cpufreq-dt wouldn't handle -EPROBE_DEFER. I'm not sure why I assumed that. As you already said: deferred probing of the regulator works fine.
> > there's still a benefit with this change: your Odroid-C1 in your > > KernelCI lab would also be able to change the CPU frequency (so in > > case something breaks we could spot it there). > > will you accept this patch after I updated the description to mention > > that it's for KernelCI test coverage? > > Possibly, but I'd still rather see the dependencies worked out correctly > so that this can be module, and cpufreq-dt would defer until it's ready. KernelCI shows multiple "pwm-regulator regulator-vcck: Failed to get PWM: -517" messages on Odroid-C1. however, what I failed to notice so far is that there's a "pwm-regulator: supplied by regulator-dummy" at the end of the boot process. does this mean that the Odroid-C1 in your KernelCI lab can load kernel modules? in that case this patch can be ignored. (I will still send a PWM regulator related patch: that "Failed to get PWM: -517" message is very noisy and we typically suppress that in other drivers) Regards Martin