Re: [PATCH v2] ASoC: soc-core: Create device_link to ensure correct suspend order

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

On Fri, Jun 19, 2026 at 02:33:36PM +0100, Richard Fitzgerald wrote:
> On 18/6/26 14:22, Marek Szyprowski wrote:
> > On 18.06.2026 15:12, Richard Fitzgerald wrote:
> > > On 18/6/26 13:58, Marek Szyprowski wrote:
> > > > On 18.06.2026 13:22, Richard Fitzgerald wrote:
> > > > > On 17/6/26 15:10, Marek Szyprowski wrote:
> > > > > > On 11.06.2026 13:08, Richard Fitzgerald wrote:
> > > Is the machine driver the parent of the codec driver?
> > 
> > Yes, so this change fixes the issue:
> 
> Right. I thought I'd tested that. But I haven't got any hardware that
> uses that "for real", so obviously I messed up my testing there.
> 
> It makes this whole device_link stuff less useful if you can't use it to
> reorder a parent-child suspend order for when the parent-child
> relationship isn't relevant to the order they should suspend.

Yeah it is pretty confusing situation if the machine driver
is the parent of the codec. What is the correct order for
things to suspend in that case? I feel like probably the parent
child relation takes precedent, but generally not making codecs
children of the machine driver seems prudent.

> If we skip entries that we can't re-order, is that simply adding
> confusing complications and _mostly_ ASoC forces the correct order, but
> in some cases it cannot and then it is up to those affected drivers to
> figure it out themselves? Can we always guarantee that those drivers
> will know which they are, or can it all break subtly because a driver
> doesn't know that in some systems it becomes related to some other
> driver?

I dunno still feels like this change is an improvement to me. The
core DAPM powers down the path, it needs the codecs available to
do that. You fix some subtle issues just not all of them.

> Mark - should we revert this because of too many corner cases in the
> device_link code and go back to every codec driver with a system_suspend
> installing its own device_link to ensure correct suspend order compared
> to the machine driver?

If you go back to this you still have a situation where ASoC
mostly does the right order it just took you more code to get
there. Also I think you would need to install the link from the
machine driver, since the codec driver could be used in
situations where it is or isn't a child of the machine driver, as
you noted earlier.

Personally I would vote for just skipping the case where the
machine driver is a parent of the card.

Thanks,
Charles