[PATCH v2 0/2] ASoC: codecs: ak4619: Add PDN pin handling

[Alexander Koch <mail@alexanderkoch.net>]

The AK4619 datasheet describes the functionality of the power down (PDN)
pin as follows (p. 39, 'Power-up/down Sequence'):

  The AK4619 should be powered up when the PDN pin = "L". The PDN pin
  should be set "H" after all power supplies have ramped up.
  At that point, the reference voltage generator block (REFBLK) and LDO
  (AVDRV) circuit are powered up and the control registers are
  initialized. Control register settings should be no less than 10ms
  after PDN pin = "H".

The current implementation of the driver does not operate the PDN pin
in any way, it seems to rely on external control of the pin.

Improve this by adding a device tree binding to enable the driver to
set the pin 'high' during probe. Make it optional to keep the behaviour
for existing device trees unchanged.

Tested on an i.MX8MM board with the AK4619 connected to GPIO1 and SSI3.


Changed in v2:
 - Fix typo in bindings update subject
 - Fix missing #include in example block for dt binding YAML
 - Improve property description in binding YAML
 - Switch property name to commonly used 'powerdown-gpios'
 - Invert GPIO logic to avoid confusion (the pin is called 'power down'
   but when driven high the chip is powered _up_)
 - Fix power leak on error after GPIO is acquired by turning the codec
   off again


Alexander Koch (2):
  ASoC: codecs: ak4619: Add optional powerdown GPIO
  ASoC: dt-bindings: asahi-kasei,ak4619: Add powerdown GPIO

 .../bindings/sound/asahi-kasei,ak4619.yaml          | 10 ++++++++++
 sound/soc/codecs/ak4619.c                           | 13 +++++++++++++
 2 files changed, 23 insertions(+)

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2.55.0