On Mon, Aug 4, 2014 at 12:18 AM, Heiko Stübner <[email protected]> wrote:
[Adding Ulf Hansson to this discussion...] > Hi Mark, Linus, > > I'd like to clarify what the appropriate way to handle pin output voltages is. > On the Rockchip SoCs the voltage for some groups of pins can be set between > 3.3V and 1.8V ... like the MMC/SD pins who need this to support UHS mode > cards. This is called "vqmmc" in the mmc/sd subsystem. grep for mmc_set_signal_voltage() in drivers/mmc/core/* In drivers/mmc/core/core.c, you find: mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc"); Which gets the regulator to set the signal voltage, if such a regulator is specified for the host. Very simple and straight-forward, and handled by the MMC core. > In [0] when talking about something different, Linus Walleij described a > similar case as > > "I think we need to have a discussion with Mark Brown on how to > handle this. > We have previously had the case of MMC/SD level-shifters, where > a certain setting gives a certain level of signals out, and another setting > gives another level. Like two discrete levels. > So we modeled that as a regulator provider inside the pin control > driver eventually, see sh-pfc/pfc-sh73a0.c" > > As this sound like exactly the thing I'm trying to solve, is handling this via > a regulator the correct general way? Ithinkso. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
