Hi,
On Fri, Oct 26, 2012 at 12:17 AM, Lucas Stach dev@lynxeye.de wrote:
Am Donnerstag, den 25.10.2012, 19:31 -0700 schrieb Simon Glass:
From: Sean Paul seanpaul@chromium.org
Add get and set gpio functions to fdtdec that take into account the polarity field in fdtdec_gpio_state.flags.
In another thread Stephen Warren and I came to the conclusion that we most likely should remove this polarity flag from the GPIO bindings.
Currently it is only for the USB VBUS GPIO which should move over to regulators once they land in U-Boot. Do you have any other applications for this flag, so we might reconsider removing it?
Well, any time you have a flag which is inverted in meaning, it can be useful. We have several switches on the board which can be active high or low, and polarity is used for that.
In fact, it would be nice IMO to be able to specify input/output as well. I know the exynos bindings do this. There is a noddy function called fdtdec_setup_gpio() in U-Boot which really needs to be sorted out. I discussed with Stephen some time ago how GPIOs should be SOC-specific and it should be possible to set up a GPIO with a single call, as Linux does. The more information there is in the binding, the more it can do automatically.
Does the Tegra Linux GPIO binding still have a polarity?
Regards, Simon