[RFC PATCH] ALSA: hda: call ext hda codec link up/down if available

[Takashi Iwai]

On Thu, 04 Feb 2021 09:07:09 +0100,
Kai Vehmanen wrote:
> 
> Hi,
> 
> On Thu, 4 Feb 2021, Kai Vehmanen wrote:
> > To support more fine-grained control of link power, this patch
> > implements new helper functions for codec drivers to turn codec links
> > up and down. The HDA common suspend/resume code is modified to use
> > the new functions. This allows to fully reuse the driver code both
> > for plain and extended HDA controllers.
> 
> Takashi and others, this patch is a follow-up to the earlier thread about 
> hdac link management:
> https://mailman.alsa-project.org/pipermail/alsa-devel/2021-January/179715.html
> 
> We have absolutely no calls from sound/pci/hda/ to hdaudio_ext.h before
> this patch, so I'm wondering if this is the right approach to take. 

An obvious drawback by this patch is that it'll make the hda-ext code
always loaded whenever it's enabled, no matter whether it's really
used or not.

Maybe adding a new callback (link) in hdac_bus_ops can help?

> It does seem to be the natural path forward and mimics what was done in 
> e.g. hdac_hdmi. But we want to keep reusing driver code for all HDA 
> implementations, so adding hdac-ext support to codec drivers seem like the 
> best path.

Yes, I find we're heading to the right direction.


thanks,

Takashi