[alsa-devel] [PATCH RFC v4 2/8] ALSA: pcm: add IEC958 channel status helper for hw_params

[Russell King - ARM Linux]

On Fri, Sep 18, 2015 at 02:06:39PM +0300, Jyri Sarha wrote:
> Add IEC958 channel status helper that gets the audio properties from
> snd_pcm_hw_params instead of snd_pcm_runtime. This is needed to
> produce the channel status bits already in audio stream configuration
> phase.

What is the reason for doing this early?

ALSA documentation (which may be out of date) says that the hw_params
callback can be called multiple times during stream setup.  Do we want
to be repeatedly programming the HDMI infoframe with different settings,
potentially confusing the attached device, or would it be better to do
it slightly later (in the prepare callback) after the parameters have
been fully negotiated?

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