Hi Maxime, On Tue, 28 Apr 2020 at 18:45, Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > 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 ? As this could take more time than expected, Could you drop the commit : add1e27fb703f65f33191ccc70dd9d811254387c arm64: dts: allwinner: h6: Enable CPU opp tables for Tanix TX6 Thanks, Clement > > Maxime
