Re: Re: [PATCH v5 5/5] Extcon: adc-jack driver to support 3.5 pi or simliar devices

[MyungJoo Ham <myungjoo.ham@samsung.com>]

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Mark Brown wrote:
> On Tue, Feb 14, 2012 at 11:22:14AM +0900, MyungJoo Ham wrote:
> > On Sat, Feb 11, 2012 at 1:25 AM, Mark Brown
> > <broonie@opensource.wolfsonmicro.com> wrote:
> > > On Fri, Feb 10, 2012 at 03:40:38PM +0900, MyungJoo Ham wrote:
> > >> External connector devices that decides connection information based on
> > >> ADC values may use adc-jack device driver. The user simply needs to
> > >> provide a table of adc range and connection states. Then, extcon
> > >> framework will automatically notify others.
> 
> > > This really should be done in terms of the IIO in-kernel framework.
> 
> > The ADC part may be done in IIO. However, the intention of this device
> > driver is to provide extcon interface to any ADC drivers, not
> > providing an ADC device driver. If we are going to implement this in
> 
> Right, exactly.
> 
> > the ADC driver in IIO, we will need to write the given code in every
> > ADC driver used for analog ports.
> 
> No, that's not what I'm suggesting - what I'm suggesting is that rather
> than having a callback for implementing the ADC read functionality this
> should work as an in-kernel IIO driver so it'll just automatically work
> with any ADC without needing code to hook things up.  Unless I've not
> understood your comment fully.

Ok. Do you mean that we should give struct iio_dev * and struct iio_chan_spec * instead of a callback?
I thought there was no standard framework for ADC (the reason why this is a simple callback); however, may I regard iio/adc as the standard for ADC? (I see some ADC device drivers in HWMON)

Do I need to make this driver as an iio device driver in order to do this? I guess including iio.h would be enough anyway.


> 
> > >> +     /* Check the length of array and set num_cables */
> > >> +     for (i = 0; data->edev.supported_cable[i]; i++)
> > >> +             ;
> > >> +     if (i == 0 || i > SUPPORTED_CABLE_MAX) {
> 
> > > Can we not avoid the hard limit?
> 
> > Without that limit, we won't be able to easily express binary cable
> > status (u32) with the extcon framework. At least, we will need to
> > forget about setting the status with u32 values.
> 
> > Anyway, I can remove the checking SUPPORT_CABLE_MAX part at probe.
> 
> It might be clearer to make the limit more obviously associated with
> the bitmask - it looks like it's an array thing the way the code is
> written but a limit due to using a bitmask seems reasonable.
> 
> 

Ah.. I'll add a comment or update the error message associated.


Cheers!
MyungJoo.

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