Re: [alsa-devel] [PATCH 1/2] ASoC: rt5677: Add ACPI device probing

[Liam Girdwood <liam.r.girdwood@linux.intel.com>]

On Tue, 2014-11-25 at 08:01 -0800, Darren Hart wrote:
> 
> On 11/25/14 06:28, Liam Girdwood wrote:
> > On Tue, 2014-11-25 at 12:11 +0000, Grant Likely wrote:
> >> On Sat, Nov 15, 2014 at 6:56 AM, Ben Zhang <benzh@chromium.org> wrote:
> >>> The rt5677 codec driver looks for ACPI device ID "RT5677CE",
> >>> which is specified in coreboot. This patch allows platform
> >>> data to be obtained via ACPI
> >>>
> >>> Signed-off-by: Ben Zhang <benzh@chromium.org>
> >>
> >> This looks like an ideal time to talk about shared DT and ACPI driver
> >> bindings. This driver /already/ has a firmware binding. It is
> >> documented in the kernel under
> >> Documentation/bindings/sound/rt5677.txt. We now have a standard method
> >> for sharing bindings between DT and ACPI in the _DSD method[1].
> >> Support for DSD is in linux-next and getting merged into v3.19. This
> >> is exactly the case that _DSD should be used for passing additional
> >> data to the driver, and it should use the existing binding.
> >>
> >> [1] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
> >>
> >> For a long time we've had the rule on DT that new bindings must be
> >> documented before we merge a patch. That rule I think has been a good
> >> one, even if it is a little chaoitc. I think when it comes to ACPI
> >> drivers that we should be requiring the same: Document the binding,
> >> either in the kernel as a DT binding, or point to somewhere else that
> >> has the binding documented.
> >>
> >> Also, since this patch is targeted at v3.19 or later, the
> >> device-properties API should be used. Don't create something custom.
> >>
> > 
> > My sentiments exactly, there would be little point having bespoke device
> > properties for every single device. Btw, we also need to align here with
> > Windows too !
> > 
> 
> The Windows folks definitely know about _DSD (and helped define it), so
> this is a good opportunity to work through that process. Liam, do you
> have a good contact to start that discussion?
> 

I do, I've contacted them off-list to align on this with Realtek.

Liam