From: Rob Herring <robh@kernel.org>
To: Florian Vaussard <florian.vaussard@heig-vd.ch>
Cc: Peter Rosin <peda@axentia.se>,
Florian Vaussard <florian.vaussard@gmail.com>,
devicetree@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>,
Hartmut Knaack <knaack.h@gmx.de>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
Slawomir Stepien <sst@poczta.fm>,
Joachim Eastwood <manabian@gmail.com>,
Matt Ranostay <mranostay@gmail.com>,
Cristina Moraru <cristina.moraru09@gmail.com>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] iio: potentiometer: mcp4531: Add device tree binding documentation
Date: Tue, 21 Jun 2016 16:37:16 -0500 [thread overview]
Message-ID: <20160621213716.GA4370@rob-hp-laptop> (raw)
In-Reply-To: <5768F180.4080601@heig-vd.ch>
On Tue, Jun 21, 2016 at 09:49:20AM +0200, Florian Vaussard wrote:
> Hello,
>
> On 06/21/2016 09:38 AM, Peter Rosin wrote:
> > On 2016-06-21 08:55, Florian Vaussard wrote:
> >> Add the device tree documentation for all the supported parts. Apart the
> >> compatible string and standard I2C binding, no other binding is currently
> >> needed.
> >>
> >> Signed-off-by: Florian Vaussard <florian.vaussard@heig-vd.ch>
> >> ---
> >> .../bindings/iio/potentiometer/mcp4531.txt | 84 ++++++++++++++++++++++
> >> 1 file changed, 84 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/mcp4531.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/mcp4531.txt b/Documentation/devicetree/bindings/iio/potentiometer/mcp4531.txt
> >> new file mode 100644
> >> index 0000000..b052299
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/iio/potentiometer/mcp4531.txt
> >> @@ -0,0 +1,84 @@
> >> +* Microchip MCP453X/454X/455X/456X/463X/464X/465X/466X Digital Potentiometer
> >> + driver
> >> +
> >> +The node for this driver must be a child node of a I2C controller, hence
> >> +all mandatory properties for your controller must be specified. See directory:
> >> +
> >> + Documentation/devicetree/bindings/i2c
> >> +
> >> +for more details.
> >> +
> >> +Required properties:
> >> + - compatible: Must be one of the following, depending on the
> >> + model:
> >> + "microchip,mcp4531-502"
> >> + "microchip,mcp4531-103"
> >> + "microchip,mcp4531-503"
> >
> > *snip*
> >
> > I'm not directly opposed, but I have used the following and DT booting
> > works like a charm here.
> >
> > mcp4651-104@28 {
> > compatible = "mcp4651-104";
> > reg = <0x28>;
> > };
> >
>
> I was not aware that the i2c subsystem had a facility to match the compatible
> string against i2c_device_id. Good to know.
>
> > But, I suppose some DT documentation is not bad, and my understanding of
> > the device instantiation process and the i2c/dt interactions are not
> > complete, so my DT snippet might be an abomination? I'll leave the
> > decision if this is needed to someone with more experience on how other
> > drivers handle this.
> >
>
> Your compatible string is missing the vendor ID (microchip). This is the only
> objection that I can see to your proposition. Let's wait to hear from a DT
> maintainer.
I2C subsystem happens to ignore the vendor prefix in matching. You
should not rely on that and provide proper compatible strings.
Rob
next prev parent reply other threads:[~2016-06-21 21:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 6:55 [PATCH 0/3] iio: potentiometer: mcp4531: New parts and device tree Florian Vaussard
2016-06-21 6:55 ` [PATCH 1/3] iio: potentiometer: mcp4531: Add support for MCP454x, MCP456x, MCP464x and MCP466x Florian Vaussard
2016-06-21 7:28 ` Peter Rosin
2016-06-21 6:55 ` [PATCH 2/3] iio: potentiometer: mcp4531: Add device tree binding documentation Florian Vaussard
2016-06-21 7:38 ` Peter Rosin
2016-06-21 7:49 ` Florian Vaussard
2016-06-21 21:37 ` Rob Herring [this message]
2016-06-21 21:43 ` Rob Herring
2016-06-22 6:19 ` Florian Vaussard
2016-06-21 6:55 ` [PATCH 3/3] iio: potentiometer: mcp4531: Add device tree binding Florian Vaussard
2016-06-21 7:34 ` kbuild test robot
2016-06-21 7:51 ` Peter Rosin
2016-06-22 6:22 ` Florian Vaussard
2016-06-22 7:06 ` Peter Rosin
2016-06-23 8:50 ` Florian Vaussard
2016-06-26 14:53 ` Jonathan Cameron
2016-06-26 14:53 ` [PATCH 0/3] iio: potentiometer: mcp4531: New parts and device tree Jonathan Cameron
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