Re: [PATCH v5 5/6] ASoC: SDCA: Create ALSA controls from DisCo

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Wed, May 14, 2025 at 02:39:20PM +0200, Pierre-Louis Bossart wrote:
> On 5/13/25 12:24, Charles Keepax wrote:
> > On Mon, May 12, 2025 at 06:14:00PM +0100, Charles Keepax wrote:
> >> On Mon, May 12, 2025 at 03:53:36PM +0200, Pierre-Louis Bossart wrote:
> >>>
> >>>> +static bool exported_control(struct sdca_control *control)
> >>>> +{
> >>>> +	/* No need to export control for something that only has one value */
> >>>> +	if (control->has_fixed)
> >>>> +		return false;
> >>>
> >>> why is that? It'd simplify userspace if there was always a way to
> >>> get a value, even if it's fixed?
> >>
> >> Well mostly it is because various things in the stack get
> >> sad with a single value control you can't set. If we wanted
> >> to change that I would suggest we add a FIXME. It isn't really
> >> critical and I would really like to get more of this class
> >> driver stuff moving, it has been out for review for a really long
> >> time now.
> >>
> > 
> > Thinking a little more about this user-space is going to have to
> > handle controls not being there as different controls will be
> > exported across different parts anyway, based of which options
> > are implemented. Also we have seen a bit of people hiding
> > controls by changing the access layer. Although sometimes that
> > does result in things that are technically not class conformant
> > but they do work through the Microsoft drivers, so we will likely
> > need to support it anyway.
> 
> Sorry, I missed what the conclusion was, would this filter stay or be removed?

Not sure I was clear either :-)

I have been poking this a little more today and I think I might
have overstated some of the problems here. I think it might be ok
to just mark the controls are read only. Will keep poking it and
will update soon, but kinda hopeful we could actually export
these in the next rev.

Thanks,
Charles