Re: [PATCH v2 2/2] leds: aw2013: Add vddio regulator

[Stephan Gerhold <stephan@gerhold.net>]

Hi Pavel,

On Thu, Mar 23, 2023 at 08:35:02PM +0100, Pavel Machek wrote:
> > Some LEDs controllers are used with external pull-up for the interrupt
> > line and the I2C lines, so we might need to enable a regulator to bring
> > the lines into usable state. Otherwise, this might cause spurious
> > interrupts and reading from I2C will fail.
> > 
> > Implement support for "vddio-supply" that is enabled by the aw2013 driver
> > so that the regulator gets enabled when needed.
> > 
> > Signed-off-by: Lin, Meng-Bo <linmengbo0689@protonmail.com>
> 
> > @@ -348,16 +350,20 @@ static int aw2013_probe(struct i2c_client *client)
> >  		goto error;
> >  	}
> >  
> > -	chip->vcc_regulator = devm_regulator_get(&client->dev, "vcc");
> > -	ret = PTR_ERR_OR_ZERO(chip->vcc_regulator);
> > -	if (ret) {
> > +	chip->regulators[0].supply = "vcc";
> > +	chip->regulators[1].supply = "vddio";
> > +	ret = devm_regulator_bulk_get(&client->dev,
> > +				      ARRAY_SIZE(chip->regulators),
> > +				      chip->regulators);
> > +	if (ret < 0) {
> >  		if (ret != -EPROBE_DEFER)
> >  			dev_err(&client->dev,
> >  				"Failed to request regulator: %d\n", ret);
> >  		goto error;
> 
> Won't this cause failures when optional vddio is unavailable?
> 

The regulator core should print a warning "supply vddio not found, using
dummy regulator" but then proceed normally.

I think in almost all cases a separate I/O supply should actually exist
that could be described in the device tree. It was likely just omitted
because it's always-on or indirectly being enabled by other devices.
So perhaps having this warning is even a good thing?

Thanks,
Stephan