[PATCH v5 00/16] ALSA/ASoC: hda: Address format selection limitations and ambiguity

Cezary Rojewski
2023-11-17T12:04:07Z

Patchset aims to address format selection restrictions present currently
in the HDAudio library. Formats which we are concerned about are 20 and
24 valid bits per sample within 32 bit depth container. One may identify
them as S20_LE and S24_LE except that those, according to comments found
in include/uapi/sound/asound.h, are for LSB-aligned scenarios. HDAudio
streams expect MSB-aligned data, no matter if we are speaking of HOST
(SDxFMT) or LINK (PPLCxFMT) side - chapter 4.5.1 of the public HDAudio
specification. In short, S20_LE and S24_LE are invalid options.

Right now, given the implementation of snd_hdac_query_supported_pcm()
within sound/hda/hdac_device.c, even if a codec responds with: "I
support all possible formats specified within HDAudio specification",
there will be no option to open a 20/32 or 24/32 stream. The kernel will
force the stream to be opened using the highest available bit depth.

After discussing subject initially with Jaroslav and Takashi, suggestion
was made to utilize 'subformat' option to address the problem. The
eye-opening discussion begun much earlier though, in 2019 [1].

Paired with PRs for alsa-utils [2] and alsa-lib [3].

Flow of changes:

The very first patch adds MSBITS subformat options to allow for granular
20/32, 24/32 and 32/32 format selection. The next two make sure
subformat is actually honored during runtime. Most of that code is based
on format-related API.

Follow up is upgrade to the hda stream-format interface - several
functions are added to make the granular format selection simple in the
HDAudio world. Core of the implementation is based on the existing
snd_hdac_calc_stream_format(). The next ten patches are straightforward
switch from one interface to another with cleanup of now-unsed function
as a finishing touch.

Last but not least - the avs-driver, on which the problem analyzed and
debugged, is updated to no longer acknowledge S24_LE as a valid format
option.

Results with skylake-driver and snd_hda_intel show status quo on our
RVPs. PR filed on SOF github shows promising results too [4].

Changes in v5:
- reworded 'bps' to 'bits' in all occurrences.
- fixed an issue of MSBITS_MAX not being reported for S32_LE as reported
by Jaroslav
- snd_pcm_subformat_width() has been inlined into its only user:
snd_pcm_hw_params_bits() as suggested by Jaroslav.
- updated commit messege for patch 01 as it was out of date given the
recent updates.

Changes in v4:
- fixed compilation issues in sof-driver, patch 12/16, reported by ikp
- fixed sparse warnings in patch 01/16, reported by ikp
- updated commit message for patch 03: "ASoC pcm: Honor subformat when
configuring runtime", as snd_pcm_hw_copy() is gone since revision v3.

Changes in v3:
- merged the first two patches as suggested by Jaroslav
- re-authored patch 01 to Jaroslav, added my Co-developed-by.
- added Jaroslav' Co-developed-by to patch 02.
- 'subformats' field now S32_LE-specific. Given the fact that it is the
only format currently requiring subformat-intervention, functionality
is narrowed to reduce amount of memory allocations and cleanup.
Suggested by Jaroslav.
- note to the above: the hdaudio part converted 1:1 as requested, patch
02/16
- note #2: alsa part converted to S32_LE-specific yet without addition
of the chicken bit. Instead, struct snd_pcm_hardware is updated with
u32 subformat mask to do the job.
- ALSA-core additions in form of snd_pcm_subformat_width() and
snd_pcm_hw_params_bps() relocated from 01/16 to the user, patch 05.

Changes in v2:
- patch 01/17, introduced struct snd_pcm_subformat which task is to
represent subformat-mask on per format basis. Expectation is that
manipulated arrays of subformats always end with a sentinel entry
- patch 01/17, added snd_pcm_hw_copy() as the copying snd_pcm_hardware
becomes non-trivial
- patch 02/17, added hw_rule that produces final subformat mask
based on provided formats as suggested by Jaroslav
- patch 04/17, soc_pcm_hw_update_subformat() refactored as the subformat
intersection becomes non-trivial
- relevant functions releasing resources occupied by hda_pcm and
snd_pcm_runtime updated to also kfree() subformats
- except for 16/17, no changes to patches past 04/17, retaining acks for
these

Changes in v1:
- fixed UBSAN due to missing snd_pcm_subformat_names[] entries for new
subformats
- as HDMI stream capabilities are assigned on PCM open, patch 16/17 has
been updated to ignore such codecs for now. A separate patchset will
take care of this case
- params_bps() reworded to snd_pcm_hw_params_bps()
- fixed compilation issues in sof-driver, patch 13/17

[1]: https://lore.kernel.org/alsa-devel/20190905053302.9262-1-pawel.harlozinski@linux.intel.com/
[2]: https://github.com/alsa-project/alsa-utils/pull/228
[3]: https://github.com/alsa-project/alsa-lib/pull/342
[4]: https://github.com/thesofproject/linux/pull/4539

Cezary Rojewski (15):
ALSA: hda: Honor subformat when querying PCMs
ASoC: pcm: Honor subformat when configuring runtime
ALSA: hda: Upgrade stream-format infrastructure
ALSA: hda: Switch to new stream-format interface
ALSA: hda/hdmi: Switch to new stream-format interface
ALSA: hda/ca0132: Switch to new stream-format interface
ASoC: codecs: hda: Switch to new stream-format interface
ASoC: codecs: hdac_hda: Switch to new stream-format interface
ASoC: codecs: hdac_hdmi: Switch to new stream-format interface
ASoC: Intel Skylake: Switch to new stream-format interface
ASoC: SOF: Intel: Switch to new stream-format interface
ASoC: Intel: avs: Switch to new stream-format interface
ALSA: hda: Drop snd_hdac_calc_stream_format()
ASoC: Intel: avs: Kill S24_LE format
ASoC: Intel: avs: Unhardcode HDAudio BE DAI drivers description

Jaroslav Kysela (1):
ALSA: pcm: Introduce MSBITS subformat interface

include/sound/hda_codec.h | 5 +-
include/sound/hdaudio.h | 13 +--
include/sound/pcm.h | 7 ++
include/sound/pcm_params.h | 2 +
include/sound/soc.h | 1 +
include/uapi/sound/asound.h | 7 +-
sound/core/pcm.c | 3 +
sound/core/pcm_lib.c | 34 +++++++
sound/core/pcm_native.c | 55 ++++++++++-
sound/hda/hdac_device.c | 156 +++++++++++++++++++++---------
sound/pci/hda/hda_codec.c | 2 +
sound/pci/hda/hda_controller.c | 10 +-
sound/pci/hda/patch_ca0132.c | 3 +-
sound/pci/hda/patch_hdmi.c | 6 +-
sound/soc/codecs/hda-dai.c | 7 +-
sound/soc/codecs/hda.c | 2 +
sound/soc/codecs/hdac_hda.c | 8 +-
sound/soc/codecs/hdac_hdmi.c | 10 +-
sound/soc/intel/avs/loader.c | 4 +-
sound/soc/intel/avs/path.c | 2 +-
sound/soc/intel/avs/pcm.c | 58 +++++++++--
sound/soc/intel/avs/probes.c | 3 +-
sound/soc/intel/avs/topology.c | 13 ++-
sound/soc/intel/skylake/skl-pcm.c | 13 ++-
sound/soc/soc-pcm.c | 10 ++
sound/soc/sof/intel/hda-dai-ops.c | 21 ++--
tools/include/uapi/sound/asound.h | 7 +-
27 files changed, 352 insertions(+), 110 deletions(-)

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2.25.1