linux-kernel - Re: [PATCH 2/3] iio: adc: ina3221: Add support for IIO ADC driver for TI INA3221

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Date:	Tue, 7 Jun 2016 15:30:58 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	"Andrew F. Davis" <afd@...com>
Cc:	Laxman Dewangan <ldewangan@...dia.com>,
	Jonathan Cameron <jic23@...nel.org>, robh+dt@...nel.org,
	corbet@....net, lars@...afoo.de, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-iio@...r.kernel.org, linux-hwmon@...r.kernel.org,
	Jean Delvare <khali@...ux-fr.org>
Subject: Re: [PATCH 2/3] iio: adc: ina3221: Add support for IIO ADC driver
 for TI INA3221

On Fri, Jun 03, 2016 at 10:17:55AM -0500, Andrew F. Davis wrote:
> On 06/03/2016 09:14 AM, Laxman Dewangan wrote:
> > 
> > On Friday 03 June 2016 06:59 PM, Guenter Roeck wrote:
> >> On 06/03/2016 03:06 AM, Jonathan Cameron wrote:
> >>> On 01/06/16 13:34, Laxman Dewangan wrote:
> >>>> The INA3221 is a three-channel, high-side current and bus voltage
> >>>> monitor
> >>>> with an I2C interface from Texas Instruments. The INA3221 monitors both
> >>>> shunt voltage drops and bus supply voltages in addition to having
> >>>> programmable conversion times and averaging modes for these signals.
> >>>> The INA3221 offers both critical and warning alerts to detect multiple
> >>>> programmable out-of-range conditions for each channel.
> >>>>
> >>>> Add support for INA3221 SW driver via IIO ADC interface. The device is
> >>>> register as iio-device and provides interface for voltage/current
> >>>> and power
> >>>> monitor. Also provide interface for setting oneshot/continuous mode and
> >>>> critical/warning threshold for the shunt voltage drop.
> >>>>
> >>>> Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
> >>> Hi Laxman,
> >>>
> >>> As ever with any driver lying on the border of IIO and hwmon, please
> >>> include
> >>> a short justification of why you need an IIO driver and also cc the
> >>> hwmon list + maintainers. (cc'd on this reply).
> >>>
> >>> I simply won't take a driver where the hwmon maintainers aren't happy.
> >>> As it stands I'm not seeing obvious reasons in the code for why this
> >>> should be an IIO device.
> >>>
> >>
> >> Me not either.
> >>
> >> I have a hwmon driver for the same chip pending from Andrew Davis (TI)
> >> which I am just about to accept. We had directed Andrew back in April
> >> to write a hwmon driver for the chip, which he did.
> >>
> > 
> > Thanks Guenter,  I found the series
> > 
> > [PATCH v2 0/2] Add support for INA3221 Triple Current/Voltage Monitors
> > Looks fine to me. I can use the hwmon.
> > 
> 
> If you search even further back you can see I originally went with an
> IIO driver as well, comparing the IIO and hwmon version for the simple
> use cases I needed the hwmod version turned out much simpler, so it was
> probably the right framework for now.
> 
> > 
> > However, some of the stuff from my patch are not there which I will add
> > later once original patch applied:
> > - Dynamic mode changes for continuous and one-shot from sysfs.
> > - In one shot, when try to read voltage data, do conversion and then read.
> > 
> 
> My attempt is rather minimal, to be honest I like your stab at this
> driver better in some ways, especially relating to DT putting each
> channel in its own node with labels, I think this is a bit more clean
> and will be more extendable if/when new multi-channel monitor chips are
> made.
> 
> > Not sure whether exporting the following will help or not. Can you
> > please confirm?
> > - Oversampling time i.e. average sample
> > - conversion time for bus voltage and shunt voltage if default is not
> > suited for system.
> > 
> > 
> 
> These can always be added as needed, but the DT changes are not as easy.
> I would like it if this got in this cycle but if you think something
> will be needed to help your improvements, that can not be added
> incrementally, it would probably be best to get them into the initial DT
> binding doc now.
> 
Andrew,

with this, the hwmon driver is pretty much on hold. What do you want me to do ?
Should I wait for DT updates ?

Guenter