[PATCH v4 0/3] simple-audio-card codec2codec support

[Samuel Holland]

We are currently using simple-audio-card on the Allwinner A64 SoC.
The digital audio codec there (sun8i-codec) has 3 AIFs, one each for the
CPU, the modem, and Bluetooth. Adding support for the secondary AIFs
requires adding codec2codec DAI links.

Since the modem and bt-sco codec DAI drivers only have one set of
possible PCM parameters (namely, 8kHz mono S16LE), there's no real
need for a machine driver to specify the DAI link configuration. The
parameters for these "simple" DAI links can be chosen automatically.

This series adds codec2codec DAI link support to simple-audio-card.
Codec to codec links are automatically detected when all DAIs in the
link belong to codec components.

I tried to reuse as much code as possible, so the first two patches
refactor a couple of helper functions to be more generic.

The last patch adds the new feature and its documentation.

Changes in v4:
  - Rebased on top of asoc/for-next, several changes to patch 2
  - Removed unused variable from patch 3
Changes in v3:
  - Update use of for_each_rtd_components for v5.6
Changes in v2:
  - Drop patch 1 as it was merged
  - Automatically detect codec2codec links instead of using a DT property

Samuel Holland (3):
  ALSA: pcm: Add a standalone version of snd_pcm_limit_hw_rates
  ASoC: pcm: Export parameter intersection logic
  ASoC: simple-card: Add support for codec2codec DAI links

 Documentation/sound/soc/codec-to-codec.rst |  9 +++-
 include/sound/pcm.h                        |  9 +++-
 include/sound/soc.h                        |  3 ++
 sound/core/pcm_misc.c                      | 18 +++----
 sound/soc/generic/simple-card-utils.c      | 48 ++++++++++++++++++
 sound/soc/soc-pcm.c                        | 59 ++++++++++++++--------
 6 files changed, 114 insertions(+), 32 deletions(-)

-- 
2.24.1