21.10.2021 16:46, Dmitry Osipenko пишет: > 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 The alternative could be to check regulator's capabilities: if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_VOLTAGE)) return 0; This looks like a better variant, actually. >> 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(). >
