Re: [PATCH v3] selftests/alsa: Test writes to IEC958 controls

[Takashi Iwai <tiwai@suse.de>]

On Sat, 12 Sep 2026 04:54:30 +0200,
HyeongJun An wrote:
> 
> Nothing checks that the put() callback of an IEC958 control reports a
> change, because write_valid skips these controls.
> 
> Where the device publishes a mask, toggle every bit in it and check each
> write.  A bit the mask advertises that does not stick fails the test, the
> way a rejected value fails for the other control types.
> 
> Where none is found, keep the old single guess at the non audio bit,
> which the device is free to ignore, so only the notification can be
> counted against it.  That path writes without checking so drop_events()
> clears what those writes leave behind.
> 
> On an HDA card with four HDMI PCMs the Con Mask is 0f ff, so each control
> walks eleven bits instead of one and all eleven stick:
> 
>   -# Totals: pass:212 fail:5 xfail:0 xpass:0 skip:56 error:0
>   +# Totals: pass:216 fail:5 xfail:0 xpass:0 skip:52 error:0
> 
> A driver whose put() never reports a change still shows up as
> event_missing.  hdmi-codec and img-spdif-out store every byte and return
> 0, so boards using them report one event_missing per walked bit, and
> hdmi-codec advertises the whole block so that is 191 of them.  A driver
> whose mask claims more than its put() keeps now fails write_valid
> outright: au88x0 and ice1712 on Delta 1010 and Mediastation advertise
> bytes they never store, cs46xx, oxygen and ice1724 advertise bits their
> put() drops, and the RME cards regenerate the whole emphasis field from
> one bit so the rest of it never reads back.  None of that hardware was
> to hand, the paths were read rather than run.
> 
> write_invalid stays a skip.  Every bit pattern is a valid channel status.
> 
> Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
> Assisted-by: Claude:claude-opus-5

Applied to for-next branch now.  Thanks.


Takashi