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@xxxxxxxxxx> > >> --- > >> .../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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html