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

[Richard Fitzgerald <rf@opensource.cirrus.com>]

On 01/06/2026 3:28 pm, Richard Fitzgerald wrote:
> In snd_soc_bind_card() create a device_link from card to all components
> to ensure correct order of system_suspend. The card is the consumer and
> the components are the supplier, so that the card will system_suspend
> before any of the components.
> 
> The PM core will normally system_suspend drivers in the opposite order
> that they registered. This ensures children are suspended before their
> parents, for example users of a bus driver should suspend before the bus
> driver suspends.
> 
> For ASoC, snd_soc_suspend() shuts down any active audio, which requires
> that the components are still able to communicate with their hardware.
> Previously there was nothing to ensure this ordering, because there is
> (usually) no relationship between a machine driver and component drivers.
> If the machine driver registered before the codec drivers, the codec
> drivers would be suspended before the machine driver snd_soc_suspend()
> runs, so that ASoC is attempting to stop audio on a driver that has
> already suspended.
> 
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
> ---
> Mark,
> I think it would be ok to put this into -next and let it get some wider
> testing before it goes into 7.1 or older.

I was looking at the Sashiko review for this patch.
If Sashiko can be trusted, device_links seems to be thoroughly
booby-trapped.

Short summary seems to be: only safe way to use them is with the
STATELESS flag and do manual cleanup.