On 10/31/2012 05:59 PM, Simon Glass wrote:

Hi,

On Fri, Oct 26, 2012 at 12:17 AM, Lucas Stach [off-list ref] wrote:

quoted

Am Donnerstag, den 25.10.2012, 19:31 -0700 schrieb Simon Glass:

quoted

From: Sean Paul <redacted>

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?

Yes it does, although in practice it can't be used (and hence should
really be removed), since not all GPIO bindings have such a flag, so
there is always a need for a separate property to indicate the polarity
(c.f. fixed-regulator with GPIO control bindings for example).