21.10.2021 16:12, Mark Brown пишет: > On Thu, Oct 21, 2021 at 02:07:07PM +0300, Dmitry Osipenko wrote: > >> Fixed regulator can't change voltage and regulator_sync_voltage() returns >> -EINVAL in this case. Make regulator_sync_voltage() to succeed for a fixed >> regulator. > >> +++ b/drivers/regulator/core.c >> @@ -4249,6 +4249,9 @@ int regulator_sync_voltage(struct regulator *regulator) >> struct regulator_voltage *voltage = ®ulator->voltage[PM_SUSPEND_ON]; >> int ret, min_uV, max_uV; >> >> + if (rdev->desc->fixed_uV && rdev->desc->n_voltages == 1) >> + return 0; >> + >> regulator_lock(rdev); > > It's unclear why this is checking both fixed_uV and n_voltages. It's unclear to me either. I borrowed this variant from the preexisting code [1][2]. [1] https://elixir.bootlin.com/linux/v5.15-rc6/source/drivers/regulator/core.c#L3075 [2] https://elixir.bootlin.com/linux/v5.15-rc6/source/drivers/regulator/core.c#L4319 > TBH > this feels like a higher level issue - with normal voltage configuration > we would have noticed that our constraints prevent the voltage changing > and not go as far as trying to actually apply a new configuration. I > would expect a similar thing to be happening here. > This works for a normal regulator_set_voltage() because it checks whether current voltage equals to the requested and then succeeds [3]. The higher level code relies on this behaviour of the regulator core, in particular OPP core won't work without it and that's why voltage changes work for a fixed regulator. [3] https://elixir.bootlin.com/linux/v5.15-rc6/source/drivers/regulator/core.c#L3619 This doesn't work for the regulator_sync_voltage() because it uses a different code path and the whole point is to re-apply the current voltage. Hence the extra check is actually needed for the fixed regulators in order to be consistent with the behaviour of regulator_set_voltage().
