ASoC: soc-pcm: Apply snd_soc_dai_link_ch_map.codec_ch_mask to codec params

In __soc_pcm_hw_params() if there is a snd_soc_dai_link_ch_map with
non-zero codec_ch_mask, use that channel mask to restrict which channels
are enabled on the codec. But only if there isn't a TDM mask.

It is possible that a snd_soc_dai_link_ch_map could include the same codec
multiple times on different CPUs so the for_each_rtd_ch_maps() loop
accumulates the channel masks for all entries of that codec.

If a TDM mask was also set, it takes priority and is used instead of any
possible snd_soc_dai_link_ch_map entries. (They cannot be ANDed together
because the bit positions are indicating different things: TDM is a bit
for each TDM slot, codec_ch_mask is a bit for each codec channel.)

This fixes a problem of incorrect TX channels enabled on the codec when
multiple codecs are aggregated on a single capture link. For example:

- Two CPUs with six 4-channel codecs.
- The machine driver chooses to assign one channel from each codec to
  one channel on the CPU
- But the codec hw_params() would be passed a channel count of 6, which
  (a) is more channels than the codec has and (b) allows enabling channels
  that should not be driving the audio bus.

Fixes: ac950278b087 ("ASoC: add N cpus to M codecs dai link support")
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20260910114500.1586637-4-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions