Re: [PATCH v3 2/4] dt-bindings: gnss: add mediatek binding

From: Johan Hovold <johan@kernel.org>
To: Loys Ollivier <lollivier@baylibre.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Rob Herring <robh@kernel.org>,
	devicetree@vger.kernel.org,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Johan Hovold <johan@kernel.org>,
	linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 2/4] dt-bindings: gnss: add mediatek binding
Date: Wed, 13 Feb 2019 10:34:25 +0100	[thread overview]
Message-ID: <20190213093425.GH28278@localhost> (raw)
In-Reply-To: <86o97iv2px.fsf@baylibre.com>

On Mon, Feb 11, 2019 at 03:06:50PM +0100, Loys Ollivier wrote:
> 
> On Mon 11 Feb 2019 at 09:22, Johan Hovold <johan@kernel.org> wrote:
> 
> > On Wed, Jan 30, 2019 at 09:50:16AM -0600, Rob Herring wrote:
> >> On Mon, Jan 28, 2019 at 05:37:59PM +0100, Loys Ollivier wrote:
> >> > Add binding for Mediatek-based GNSS receivers.
> >> > 
> >> > Signed-off-by: Loys Ollivier <lollivier@baylibre.com>

> >> reset-gpios is the standard name.
> >> 
> >> > +- gtop,fix-gpios	: GPIO used to determine device position fix state
> >> > +			  (pin name: FIX, 3D_FIX)
> >
> > I'm thinking we might need a standard name for fix-gpios as well. This
> > isn't a feature that is globaltop (or mediatek) specific, and other
> > manufacturers provide similar functionality through pins named UI_FIX,
> > or even LCKIND (lock indicator).
> >
> > The pin is typically used to drive an indicator LED AFAIU, but the
> > characteristics of the signal varies from device to device (fw to fw),
> > for example, pulse when no lock and low otherwise, or pulse when a 2d or
> > 3d-fix is acquired, etc.
> >
> 
> Yes most GNSS recevivers provide a similar feature even if behavior of
> the line differs.
> 
> > I'm not sure how useful the pulsing would be for software, but someone
> > might find a use for it in some form.
> >
> 
> Well it is useful to know when you start acquiring "valid" positionning
> data. I'm using this as a trigger to start recording position.

Sure, but a non-pulsing signal might have been easier to deal with if it
was meant to be used by software.

> > Rob, is this something we want to keep in the binding, and if so, how
> > about using a generic name such as "gnss-fix-gpios"?
> 
> Name "gnss-fix-gpios" sounds good to me.

Let's go with that then.

Johan

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