* Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx> [120305 07:35]: > 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, with the intention of updating both drivers to manipulate that > regulator, not the GPIO pin directly. > > Before the ASoC driver is updated and the modem platform data expanded > with a power management callback for switching its power, the > ams_delta_latch_write() function, which still provides the old API for > accessing latch2 functionality from not updated drivers, is modified to > toggle the regulator instead of the MODEM_NRESET GPIO pin. A helper > function provided for balancing the regulator enable/disable operations, > together with the consumer data needed for tracking the regulator state, > will be removed once the drivers are updated. > > Depends on patch series "ARM: OMAP1: ams-delta: replace custom I/O with > GPIO". > > Signed-off-by: Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx> > --- > v2 -> v3 changes: > * fix section mismatch isue. > > Changes against initial version: > * rename consumer setup elements to match their final, modem only > related purpose, > * initialize the regulator pointer and mutex before first use, then > omit testing that pointer against NULL value Thanks, applying all three into ams-delta branch. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
