[alsa-devel] [PATCH v2 0/4] Amstrad Delta: access MODEM_RESET GPIO pin over a regulator

Janusz Krzysztofik jkrzyszt at tis.icnet.pl
Fri Dec 30 04:04:52 CET 2011

The Amstrad Delta on-board latch2 bit named MODEM_NRESET, now available
as a GPIO pin AMS_DELTA_GPIO_PIN_NMODEM_RESET, is used to power up/down
(bring into/out of a reset state) two distinct on-board devices
simultaneously: the modem, and the voice codec. As a consequence, that
bit is, or can be, manipulated concurrently by two drivers, or their
platform provided hooks.

Instead of updating those drivers to use the gpiolib API as a new method
of controlling the MODEM_NRESET pin state, like it was done to other
drivers accessing latch2 pins, and still being vulnerable to potential
concurrency conflicts, or trying to solve that sharing issue with a
custom piece of code, set up a fixed regulator device on top of that
GPIO pin and update both drivers to manipulate that regulator, not the
GPIO pin directly.

Changes against initial version:
* in both the codec and the modem callbacks, don't track the regulator
  enable/disable state, compare new targert bias level (the codec case)
  or power state (the modem case) with the old value instead; thanks to
  Mark Brown who suggested this solution,
* a few other minor changes, mostly stylistic.

Janusz Krzysztofik (4):
  ARM: OMAP1: ams-delta: set up regulator over modem reset GPIO pin
  ASoC: cx20442: add bias control over a platform provided regulator
  ARM: OMAP1: ams-delta: update the modem to use regulator API
  ASoC: OMAP: ams-delta: drop .set_bias_level callback

 arch/arm/mach-omap1/Kconfig                       |    2 +
 arch/arm/mach-omap1/board-ams-delta.c             |   94 +++++++++++++++++++--
 arch/arm/plat-omap/include/plat/board-ams-delta.h |    1 -
 sound/soc/codecs/cx20442.c                        |   48 ++++++++++-
 sound/soc/omap/ams-delta.c                        |   34 --------
 5 files changed, 133 insertions(+), 46 deletions(-)


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