On Fri, Aug 02, 2019 at 09:32:17AM +0100, Thomas Preston wrote:
> On 02/08/2019 00:42, Mark Brown wrote:

> > Yes, that's definitely doable - we've got some other drivers with
> > similar things like calibration triggers exposed that way.

> One problem with using a kcontrol as a trigger for the turn-on diagnostic
> is that the diagnostic routine has a "return value".

You can use a read only control for the readback, or just have it be
triggered by overwriting the readback value.  You can cache the result.

> Hm, maybe a better idea is to have the turn on diagnostic only run on
> device probe (as its name suggests!), and print something to dmesg:

> 	modprobe tda7802 turn_on_diagnostic=1

> 	tda7802-codec i2c-TDA7802:00: Turn on diagnostic 04 04 04 04

> Kirill Marinushkin mentioned this in the first review [0], it just didn't
> really sink in until now!

You could do that too, yeah.  Depends on what this is diagnosing and if
that'd be useful.