Re: [PATCH 19/19] ASoC: amd: ps: increase runtime suspend delay

[Limonciello, Mario]

On 1/12/2023 08:54, Pierre-Louis Bossart wrote:
> On 1/12/23 05:02, Mukunda,Vijendar wrote:
> > On 11/01/23 21:32, Pierre-Louis Bossart wrote:
> > > On 1/11/23 03:02, Vijendar Mukunda wrote:
> > > > To avoid ACP entering into D3 state during slave enumeration and
> > > > initialization on two soundwire controller instances for multiple codecs,
> > > > increase the runtime suspend delay to 3 seconds.
> > > You have a parent PCI device and a set of child devices for each
> > > manager. The parent PCI device cannot suspend before all its children
> > > are also suspended, so shouldn't the delay be modified at the manager level?
> > >
> > > Not getting what this delay is and how this would deal with a lengthy
> > > enumeration/initialization process.
> > Yes agreed. Until Child devices are suspended, parent device will
> > be in D0 state. We will rephrase the commit message.
> >
> > Machine driver node will be created by ACP PCI driver.
> > We have added delay in machine driver to make sure
> > two manager instances completes codec enumeration and
> > peripheral initialization before registering the sound card.
> > Without adding delay in machine driver will result early card
> > registration before codec initialization is completed. Manager
> > will enter in to bad state due to codec read/write failures.
> > We are intended to keep the ACP in D0 state, till sound card
> > is created and jack controls are initialized. To handle, at manager
> > level increased runtime suspend delay.
>
> This doesn't look too good. You should not assume any timing
> dependencies in the machine driver probe. I made that mistake in earlier
> versions and we had to revisit all this to make sure drivers could be
> bound/unbound at any time.

Rather than a timing dependency, could you perhaps prohibit runtime PM 
and have a codec make a callback to indicate it's fully initialized and 
then allow runtime PM again?