[Linux-stm32] [PATCH 00/17] ASoC: remove snd_soc_dai_set_tristate()

[Richard Fitzgerald]

On 09/12/2024 9:52 am, Charles Keepax wrote:
> On Mon, Dec 09, 2024 at 07:38:52AM +0000, Kuninori Morimoto wrote:
>> Hi Mark
>>
>> snd_soc_dai_set_tristate() has added in v2.6.27 (2008/Oct) by this commit
>>
>> 	8c6529dbf881303920a415c2d14a500218661949
>> 	("ALSA: asoc: core - add Digital Audio Interface (DAI) control functions.")
>>
>> But it has never been used during this 16 years.
>> Let's remove it.
> 
> We have definitely used it in out of tree code for some phones in
> our times. Whilst I don't feel super strongly, I would say it seems
> like fairly reasonable functionality and it does no harm, so I
> would vote to keep it.
> 
> Thanks,
> Charles

Yes, I'd forgotten that this function even existed. Now I've been
reminded of it, it's a useful function because our I2S/TDM DAIs have
configurable tri-stating. If we remove the function the alternative
of using a pinmux driver is a lot of overhead.

But the kerneldoc description is not very good:

"Tristates the DAI so that others can use it."

That makes it sound like it disables the DAI. Should it say "Set the DAI
TX pin to be hi-impedance in TDM slots where it is not transmitting"?