This function is base on the accelerator implementation
for compress API:
https://patchwork.kernel.org/project/alsa-devel/patch/20241002093904.1809799-1-perex@perex.cz/

Audio signal processing also has the requirement for memory to
memory similar as Video.

This asrc memory to memory (memory ->asrc->memory) case is a non
real time use case.

User fills the input buffer to the asrc module, after conversion, then asrc
sends back the output buffer to user. So it is not a traditional ALSA playback
and capture case.

Because we had implemented the "memory -> asrc ->i2s device-> codec"
use case in ALSA.  Now the "memory->asrc->memory" needs
to reuse the code in asrc driver, so the patch 1 and patch 2 is for refining
the code to make it can be shared by the "memory->asrc->memory"
driver.

Other change is to add memory to memory support for two kinds of i.MX ASRC
modules.

changes in v5:
- Drop Jaroslav Kysela's patch as it has been merged.
- Add Jaroslav Kysela's Acked-by tag, received in v3.

changes in v4:
- remove the RFC tag, no comments receive in v3
- Add Jaroslav Kysela's patch in this patch set. because it may be
  better for reviewing in a full patch set.
- Fix the list_for_each_entry_reverse to list_for_each_entry_safe_reverse
- Fix some coding style issues in Jaroslav Kysela's patch

changes in v3:
- use Jaroslav's suggestion for header file compress_params.h (PATCH 01)
- remove the ASRC_OUTPUT_FORMAT/ASRC_OUTPUT_RATE definition
- remove ASRC_RATIO_MOD in this version because it uses .set_metadata()
  Will wait Jaroslav's update or other better method in the future.
- Address some comments from Pierre.

changes in v2:
- Remove the changes in compress API
- drop the SNDRV_COMPRESS_SRC_RATIO_MOD
- drop the SND_AUDIOCODEC_SRC and struct snd_dec_src
- define private metadata key value
  ASRC_OUTPUT_FORMAT/ASRC_OUTPUT_RATE/ASRC_RATIO_MOD

Shengjiu Wang (6):
  ALSA: compress: Add output rate and output format support
  ASoC: fsl_asrc: define functions for memory to memory usage
  ASoC: fsl_easrc: define functions for memory to memory usage
  ASoC: fsl_asrc_m2m: Add memory to memory function
  ASoC: fsl_asrc: register m2m platform device
  ASoC: fsl_easrc: register m2m platform device

 include/uapi/sound/compress_params.h |  23 +-
 sound/soc/fsl/Kconfig                |   1 +
 sound/soc/fsl/Makefile               |   2 +-
 sound/soc/fsl/fsl_asrc.c             | 179 ++++++-
 sound/soc/fsl/fsl_asrc.h             |   2 +
 sound/soc/fsl/fsl_asrc_common.h      |  70 +++
 sound/soc/fsl/fsl_asrc_m2m.c         | 727 +++++++++++++++++++++++++++
 sound/soc/fsl/fsl_easrc.c            | 261 +++++++++-
 sound/soc/fsl/fsl_easrc.h            |   4 +
 9 files changed, 1260 insertions(+), 9 deletions(-)
 create mode 100644 sound/soc/fsl/fsl_asrc_m2m.c

-- 
2.34.1