Re: [PATCH v2 4/8] dt-bindings: gnss: add u-blox binding

[Johan Hovold <johan@kernel.org>]

On Thu, May 31, 2018 at 08:55:10AM -0500, Rob Herring wrote:
> On Thu, May 31, 2018 at 3:22 AM, Johan Hovold <johan@kernel.org> wrote:
> > On Wed, May 30, 2018 at 10:58:05PM -0500, Rob Herring wrote:
> >> On Wed, May 30, 2018 at 12:32:38PM +0200, Johan Hovold wrote:
> >> > Add binding for u-blox GNSS receivers.
> >> >
> >> > Note that the u-blox product names encodes form factor (e.g. "neo"),
> >> > chipset (e.g. "8") and variant (e.g. "q"), but that only formfactor and
> >> > chipset is used for the compatible strings (for now).
> >> >
> >> > Signed-off-by: Johan Hovold <johan@kernel.org>
> >> > ---
> >> >  .../devicetree/bindings/gnss/u-blox.txt       | 44 +++++++++++++++++++
> >> >  .../devicetree/bindings/vendor-prefixes.txt   |  1 +
> >> >  2 files changed, 45 insertions(+)
> >> >  create mode 100644 Documentation/devicetree/bindings/gnss/u-blox.txt
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/gnss/u-blox.txt b/Documentation/devicetree/bindings/gnss/u-blox.txt
> >> > new file mode 100644
> >> > index 000000000000..caef9ace0b0c
> >> > --- /dev/null
> >> > +++ b/Documentation/devicetree/bindings/gnss/u-blox.txt
> >> > @@ -0,0 +1,44 @@
> >> > +u-blox GNSS Receiver DT binding
> >> > +
> >> > +The u-blox GNSS receivers can use UART, DDC (I2C), SPI and USB interfaces.
> >> > +
> >> > +Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic
> >> > +properties.
> >> > +
> >> > +Required properties:
> >> > +
> >> > +- compatible       : Must be one of
> >>
> >> mixture of space and tab here.
> >
> > Oops. Same single space character before the tab here in all three
> > binding docs (and in the in-tree slave_devices.txt which I think I used
> > as a template).
> 
> Who wrote that crap? ;)

Heh.

> >
> >> > +
> >> > +                   "u-blox,neo-8"
> >> > +                   "u-blox,neo-m8"
> >> > +
> >> > +- vcc-supply       : Main voltage regulator
> >> > +
> >> > +Required properties (DDC):
> >> > +- reg              : DDC (I2C) slave address
> >> > +
> >> > +Required properties (SPI):
> >> > +- reg              : SPI chip select address
> >> > +
> >> > +Required properties (USB):
> >> > +- reg              : Number of the USB hub port or the USB host-controller port
> >> > +                  to which this device is attached
> >> > +
> >> > +Optional properties:
> >> > +
> >> > +- timepulse-gpios  : Time pulse GPIO
> >> > +- u-blox,extint-gpios      : External interrupt GPIO
> >>
> >> This should be interrupts property instead of a gpio.
> >
> > Contrary to what the name may suggest, this pin is actually an input
> > which can be used to control active power or to provide time or
> > frequency aiding data to the receiver (see section 1.13 in [1]).
> >
> > I only added it for completeness as the driver does not use it
> > currently. Remove, leave as is, or add "input" to the description as in:
> >
> >         - u-blox,extint-gpios   : External interrupt input GPIO
> 
> Yes. You should also define the active level.

The active level appears to be runtime configurable and dependent on the
selected function. For power control it can be used to control force-on
(active high), force-off (active low) or both; and for time aiding
sampling on falling or rising edge is also configurable. And who knows
what else this pin is used for next time they update the firmware. ;)

Shall I remove the property, or just add "input" as suggested above?

Thanks,
Johan