Re: [PATCH V4 2/2] thermal: generic-adc: Add ADC based thermal sensor driver

[Laxman Dewangan]

On Thursday 21 April 2016 05:13 AM, Eduardo Valentin wrote:
> Laxman,
>
> On Tue, Apr 19, 2016 at 12:52:01PM +0530, Laxman Dewangan wrote:
> > In some of platform, thermal sensors like NCT thermistors are
> > connected to the one of ADC channel. The temperature is read by
> > reading the voltage across the sensor resistance via ADC. Lookup
> > table for ADC read value to temperature is referred to get
> > temperature. ADC is read via IIO framework.
> >
> > Add support for thermal sensor driver which read the voltage across
> > sensor resistance from ADC through IIO framework.
> >
> > Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> I really like this driver, as I mentioned  before. Just one comment
> though.
>
> > +
> > +	gti->tz_dev = thermal_zone_of_sensor_register(&pdev->dev, 0,
> > +						      gti, &gadc_thermal_ops);
> Why not using the devm_ version you introduced?
>
> Any particular reason?

Yaah, the reason is just to maintain the proper sequence in releasing of 
resource during driver unbinding.

Sequence in probe are:
        iio_channel_get()
        thermal_zone_of_sensor_register()

and on release, sensor should be released first before iio channel.
As of now, we do not have devm_iio_channel_get() [I already post patch 
and it is accepted by Jonathan in iio sub system] and hence I can not 
use the devm_ for sensor register to avoid race.

However, once the devm_ for iio channel get available in all subsystem 
(may be in next release), I will post the patch to use devm_.

Currently, we can go with these APIs.