On Tue, Apr 28, 2020 at 06:23:35PM +0200, Clément Péron wrote: > Hi Robin, > > On Tue, 28 Apr 2020 at 17:21, Robin Murphy <robin.murphy@xxxxxxx> wrote: > > > > On 2020-04-28 3:26 pm, Clément Péron wrote: > > > Tanix TX6 has a fixed regulator. As DVFS is instructed to change > > > voltage to meet OPP table, the DVFS is not working as expected. > > > > Hmm, isn't that really a bug in the DVFS code? I guess it's just blindly > > propagating -EINVAL from the fixed regulators not implementing > > set_voltage, but AFAICS it has no real excuse not to be cleverer and > > still allow switching frequency as long as the voltage *is* high enough > > for the given OPP. I wonder how well it works if the regulator is > > programmable but shared with other consumers... that case probably can't > > be hacked around in DT. > > Like you, I thought that the DVFS was clever enough to understand this > but guess not.. > > Maybe they are some cases where you don't want to leave the voltage high and > reduce the frequency. But I don't know such case. I assume the intent was to prevent a regulator driver to overshoot and end up over-volting the CPU which would be pretty bad. I guess we could check that the voltage is in the range opp < actual voltage < max opp voltage ? Maxime
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