tree 2428cd0ce337053475d4aeab6d7f58fc2115490f
parent 0db0c62c88b84b135bbaf784499a08e536354a43
author Katsuhiro Suzuki <katsuhiro@katsuster.net> 1567874213 +0900
committer Mark Brown <broonie@kernel.org> 1568022636 +0100
gpgsig -----BEGIN PGP SIGNATURE-----
 
 iQFHBAABCgAxFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl12IGwTHGJyb29uaWVA
 a2VybmVsLm9yZwAKCRAk1otyXVSH0B5WB/wI9PovBd1uULgRP5qLkHjb/cahiZt9
 r2IJMMWTZVG0wkZvjpzIsZdFDSE5mszIRPZ/D0r52QZeUe59vQuTYpUTBRC5ogKB
 4biRJ6ESp3HKKFoT9i5LESaD3oLPnpdMM7V0KoQ9LW4cDKU0+BLtq1C1PEhhh7ZF
 KbsomRIfuo74oGbdIWjK+8Gt5wv3qd6MA62u7VMY7f093yjjZrxZwrFDTQaxG/Jl
 IzpwzEYx+ISFnIeXE9n32LenT2QsLJfNjALQj71s5OR5SOt35WaSxY6YZI2mXoJq
 qJEf56x/N7+EOuoF6qY4RcxJN8sHRKHQ7Vq+faAugY/NMVDeJ8wPF9uJ
 =HQL0
 -----END PGP SIGNATURE-----

ASoC: es8316: support fixed and variable both clock rates

This patch supports some type of machine drivers that set 0 to mclk
when sound device goes to idle state. After applied this patch,
sysclk == 0 means there is no constraint of sound rate and other
values will set constraints which is derived by sysclk setting.

Original code refuses sysclk == 0 setting. But some boards and SoC
(such as RockPro64 and RockChip I2S) has connected SoC MCLK out to
ES8316 MCLK in. In this case, SoC side I2S will choose suitable
frequency of MCLK such as fs * mclk-fs when user starts playing or
capturing.

Bad scenario as follows (mclk-fs = 256):
  - Initialize sysclk by correct value (Ex. 12.288MHz)
    - ES8316 set constraints of PCM rate by sysclk
      48kHz (1/256), 32kHz (1/384), 30.720kHz (1/400),
      24kHz (1/512), 16kHz (1/768), 12kHz (1/1024)
  - Play 48kHz sound, it's acceptable
  - Sysclk is not changed

  - Play 32kHz sound, it's acceptable
  - Set sysclk by 8.192MHz (= fs * mclk-fs = 32k * 256)
    - ES8316 set constraints of PCM rate by sysclk
      32kHz (1/256), 21.33kHz (1/384), 20.48kHz (1/400),
      16kHz (1/512), 10.66kHz (1/768), 8kHz (1/1024)

  - Play 48kHz again, but it's NOT acceptable because constraints
    list does not allow 48kHz

Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Link: https://lore.kernel.org/r/20190907163653.9382-2-katsuhiro@katsuster.net
Signed-off-by: Mark Brown <broonie@kernel.org>