On 2022-11-05 12:54 AM, Mark Brown wrote:
On Fri, Nov 04, 2022 at 09:58:46AM -0400, Pierre-Louis Bossart wrote:
If I follow your logic, we should also remove the workqueue used for
probes for HDaudio devices, on the grounds that probe errors are not
propagated either.
(save)
Any time we have deferred processing to avoid blocking the rest of the
system, we incur the risk of not having errors propagated. It's a
compromise between having a system that's usable and a system that's
consistent.
The other question is what we'd constructively do about a resume failure
that we can't defer. It feels like we should at least retain the
ability to defer for devices where this is an issue (older components
tend to be cheap and packaged in easier to assemble packaging and hence
get used with lower end applications even well after they're no longer
competitive at the high end), and if we are going to return some errors
in line it'd be good to understand the benefits and tradeoffs. I do see
that it is a lot less useful for modern devices where we don't have to
have any delays in startup, though like I say register I/O on slower
buses like I2C could still be a concern.
I'm not keen on moving the support out of the core since there were
originally a bunch of devices trying to open code and it wasn't good,
both from a duplication/complexity point of view and from the point of
view of integrating well with userspace APIs.
I believe that framework should be supporting both, the deferred and the
instant resume options. 'void' in front of suspend/resume in ASoC
hinders developer's options.
(load)
The HDAudio driver is actually a good example of how to do it right - we
did not modify driver/base/ to have ->probe() return void. It remained
as is, instead, a developer opt-ins for a delayed probe through a
workqueue. This way, everyone is satisfied.
Cohesiveness is not to be forgotten too - keeping behavior and
expectations of the standard set of functionalities aligned with the
rest of the driver/base makes it easier to hop into ASoC.
We could provide some additional flags so that the ASoC core always
defers PM-related work for certain components if they choose to.
Regards,
Czarek
