Re: [PATCH v2] selftests/alsa: Test writes to IEC958 controls

[Mark Brown]

On Fri, Sep 11, 2026 at 10:44:16PM +0900, HyeongJun An wrote:
> On Tue, Sep 08, 2026 at 05:23:19PM +0100, Mark Brown wrote:

> > It seems like we should have a test that we can actually find this
> > control, right now it looks like we silently ignore it being missing.
> > Are all IEC958 controls supposed to have one of these?

> I couldn't find anything saying they must. 32 of the 36 writable
> Playback Defaults in the tree have a Con Mask, Pro Mask or Mask sibling,
> 4 don't (fsl_spdif, fsl_xcvr, uniperif_player, stm32_sai_sub). The
> driver docs only ask that mask and default share an iface, and
> sound/core doesn't check. So unless there's a rule I'm missing I'll keep
> the non audio guess for those and print that no mask was found, rather
> than fail them.

I dunno, if 32 of 36 have a mask that sounds more like there is a
standard for all practical purposes but we've got a few drivers that
could be improved to better implement things.  This is quite common with
mixer-test - we generally enforce things relatively laxly compared to
the spec.  It's probably more helpful all round to add the missing mixer
controls.

> One thing I'd like to check with you first. Failing on an advertised
> bit that's dropped turns three drivers that pass today into failures:
> au88x0 (mask says 0xff, put() reads only the FS bits), ice1712 on Delta
> 1010 and Mediastation (mask 0xff, no put callback), and rme32 in
> professional layout (mask advertises the whole emphasis field, the
> converter reads one value). I think those are the mask not matching the
> driver, which is the kind of thing the test is for, but I don't have
> any of that hardware. I'll go with strict for v3 unless you'd rather
> those were reported without failing. Happy to do either.

Yes, I think this is a reasonable thing to add - like I was saying above
it's realtively common given our lack of enforcement and general driver
quality for us to see existing bugs.  Hopefully someone with the
hardware will notice and take a look, or if they don't perhaps it's not
actually causing them problems anyway.

Thanks for working on this!

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