RE: [alsa-devel] [PATCH v2] ASoC: da7219: read fmw property to get mclk for non-dts systems

[Adam Thomson]

On 03 May 2018 02:39, Mark Brown wrote:

> On Wed, May 02, 2018 at 10:13:55AM +0000, Adam Thomson wrote:
> > On 01 May 2018 21:50, Mark Brown wrote:
> 
> > > There's a lot of things that ACPI *should* do but doesn't - it's a bit
> > > of a shambles how ACPI standards get defined and what's there is not
> > > really intended to handle systems like these semi-embedded ones.  One of
> > > the big gaps in ACPI is that it has no handling at all of clocks, that's
> > > supposed to be done transparently by firmware in the ACPI model.  What a
> > > lot of the embedded Intel people have been doing is coopting the DT
> > > bindings wholesale for ACPI systems but that has problems when you get
> > > into areas which should be handled in some way on ACPI systems like
> > > power and unfortunately clocks are kind of power adjacent so might be a
> > > bit sketchy here.
> 
> > Yes I was aware that previously that was the case, although have not followed
> > this for a while. It just feels here that we should aim for something more
> > generic rather than a device specific property/binding, if possible, as that
> > feels messy to me and I'm sure other drivers could take advantage of this as
> > well. I've not looked at the clock code in too much detail though, at least with
> > regards to this area, so not sure how feasible that is.
> 
> > As a suggestion for ACPI would it be possible to re-use the 'clock-names'
> > property and add something in the framework to handle this?
> 
> I completely agree that ACPI should have handling for clocks but it
> really feels like something that should be done as a proper spec rather
> than just ad hoc by Linux like the x86 embedded people often do - it's
> too close to the power management stuff that ACPI definitely does
> handle.

Yep, agreed. Be nice if someone could do that rather than us having workarounds.