[Bug 91410] [BDW][Audio][HD-A Display] DP/HDMI audio playback abnormal

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=91410

Ville Syrjala <ville.syrjala at linux.intel.com> changed:

           What    |Removed                     |Added
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                 CC|                            |tiwai at suse.de

--- Comment #25 from Ville Syrjala <ville.syrjala at linux.intel.com> ---
(In reply to Jim Bride from comment #24)
> I'm not so sure that this is a race per se.  From the brief look I took at
> the HDA driver, it seems that the audio code believes that CDCLK stays at a
> fixed value and thus it only confirms the value during its initial init and
> when a resume operation occurs.  Since CDCLK can be changed at various times
> on some platforms, it seems like what we need is some sort of a callback
> mechanism to notify the audio driver when CDCLK gets set to a new value so
> that they can update their M/N values appropriately.  Alternately, although
> I'd leave this determination to folks that are more familiar with the audio
> driver, if there's a good spot where they can call
> snd_hdac_get_display_clk() periodically and update their M/N values if the
> new value differs from the previous value that they have then that would
> work too.  Thoughts?

We have the .pin_eld_notify() hook which could trigger the audio driver to
re-query the cdclk. If the port is enabled, cdclk is currently guaranteed to
stay at a fixed frequency between the .pin_eld_notify() calls from the port
enable and disable.

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