On Tue, Sep 11, 2012 at 1:00 PM, zhangfei gao <zhangfei.gao@xxxxxxxxx> wrote: > On Sun, Sep 9, 2012 at 11:06 AM, Chris Ball <cjb@xxxxxxxxxx> wrote: >> Tested on OLPC XO-4/MMP3, where the card power for two of the >> controllers is a sideband GPIO. The third cell in the power-gpios >> property controls whether the GPIO is active high/active low. >> >> (Also, pass host_caps2 through from platdata to the mmc host.) >> >> Signed-off-by: Chris Ball <cjb@xxxxxxxxxx> >> --- >> This patch depends on "mmc: slot-gpio: Add support for power gpios" >> >> drivers/mmc/host/sdhci-pxav3.c | 25 +++++++++++++++++++++++++ >> include/linux/platform_data/pxa_sdhci.h | 2 ++ >> 2 files changed, 27 insertions(+) > > Thanks Chris. > One questions is could we simply use fixed voltage regulator to control gpio? > And register this gpio as vmmc. > > Thanks Hi Chris, As my understanding, the buck/LDO supplies power to MMC slot with 2.8V. We can call it as regulator A. GPIO pin is used to control this power supply to MMC slot. We can call it as regulator B (fixed regulator). I think that we can linked these two regulators as cascade. Since we won't change voltage as regulator A. This link won't bring us any issue. So we only need to control regulator B in mmc driver. How do you think about this idea? Regards Haojian -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
