ASoC: soc-pcm: constrain hw_params when DAIs share the same BCLK

When multiple CPU DAIs on the same sound card share the same physical
BCLK, add a hw_rule during PCM open that constrains the sample rate so
the resulting BCLK rate stays consistent across all sharing DAIs.

The rule callback scans all DAIs on the card at hw_refine time, looking
for an active peer that shares the same physical BCLK (via
clk_is_match()) and has already completed hw_params (checked via
dai->symmetric_rate != 0). This ensures the constraint uses the real
BCLK rate established by the peer's clk_set_rate() in hw_params, not a
stale boot-time default.

The first DAI to complete hw_params is unconstrained (no active peer
yet); subsequent DAIs are constrained to match.

The rule supports two modes:
- If the DAI has an explicit bclk_ratio set (e.g. for TDM where
  BCLK = rate * slots * slot_width), the rate is constrained to
  active_bclk_rate / bclk_ratio.
- Otherwise, the default formula BCLK = rate * channels * sample_bits
  is used to derive the valid rate range.

The constraint is purely additive: DAIs that do not set a bclk clock
pointer are completely unaffected.

Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Link: https://patch.msgid.link/20260522-i2s-same-blk-v4-3-a71a86faaa20@linux.spacemit.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions