Re: [PATCH v3 5/5] usb: typec: tcpm/tcpci_maxim: deprecate WAR for setting charger mode

[Amit Sunil Dhamne <amitsd@google.com>]

Hi Heikki,

Thanks for the review!

On 1/9/26 5:14 AM, Heikki Krogerus wrote:
> Hi,
>
>> +	if (source) {
>> +		if (!regulator_is_enabled(chip->vbus_reg))
>> +			ret = regulator_enable(chip->vbus_reg);
>> +	} else {
>> +		if (regulator_is_enabled(chip->vbus_reg))
>> +			ret = regulator_disable(chip->vbus_reg);
>> +	}
> It looks like you have to do one more round, so can drop the
> regulator_is_enabled() checks and just always enable/disable it
> unconditionally.
>
>         if (source)
> 		ret = regulator_enable(chip->vbus_reg);
> 	else
> 		ret = regulator_disable(chip->vbus_reg);

The regulator framework uses refcounting on the number of enables. If
the number of times regulator is disabled > enabled, a warning will be
thrown. Also, I don't want to call regulator_enable more than once for
the same refcounting reason (will have to call disable those many number
of times to actually disable).

> I don't think you need the check in any case, but if I've understood
> this correctly, you should not use that check when the regulator does
> not support that check because then the API claims it's always
> enabled. So I guess in that case "if (!regulator_is_enabled())" may
> not work as expected, and you may actually be left with a disabled
> regulator. This may not be a problem on current platforms, but who
> knows what happens in the future.

I don't think this should be an issue in the future as this driver is
specifically meant for max77759_tcpci device and should only be used
with max77759 charger (they both exist only in the same package). And
that the max77759_charger driver does implement the callback. However,
if you think that regulator_is_enabled() is unreliable, I could track
the state within the tcpci driver instead of calling
regulator_is_enabled() and call enable/disable regulator accordingly.

Let me know wdyt and I'll update the next revision accordingly.


BR,

Amit

>
> thanks,
>