[alsa-devel] [PATCH 2/3] ALSA - hda: Add support for link audio time reporting

[Takashi Iwai]

On Fri, 15 Jul 2016 07:39:10 +0200,
Vinod Koul wrote:
> 
> On Fri, Jul 15, 2016 at 07:17:14AM +0200, Takashi Iwai wrote:
> > On Fri, 15 Jul 2016 07:19:06 +0200,
> > Vinod Koul wrote:
> > > > > > >> sound/pci/hda/hda_controller.c:30:21: fatal error: asm/tsc.h: No such file or directory
> > > > > >    compilation terminated.
> > > > > 
> > > > > Okay i think I need to move this bit into the intel code.
> > > > > 
> > > > > Takashi, I didnt see any X86 depends on SND_HDA_INTEL. I think we should add
> > > > > this now. Are you okay with that?
> > > > 
> > > > Better to have an explicit ifdef CONFIG_X86 around it.  It's not only
> > > > for x86.
> > > 
> > > Need it around the whole of the timestamp code as well then..
> > 
> > Yes.  But why TSC is mandatory?  There is no explanation in your
> > patch.
> 
> HW reports ART values and we need to convert these to TSC.
> 
> The callflow is that the azx_get_crosststamp is called which invokes
> get_device_system_crosststamp() and calls azx_get_sync_time callback.
> 
> So dependency is around convert_art_to_tsc() which is x86 API.

How is defined in the spec?  I wonder it because HD-audio spec itself
is usually CPU-neutral.


Takashi

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