Re: [PATCH v8 09/12] dt-bindings: mux-adg792a: document devicetree bindings for ADG792A/G mux

[Peter Meerwald-Stadler <pmeerw@pmeerw.net>]

On Fri, 27 Jan 2017, Peter Rosin wrote:

comments below, picking on typos

> On 2017-01-27 20:50, Rob Herring wrote:
> > On Wed, Jan 18, 2017 at 04:57:12PM +0100, Peter Rosin wrote:
> >> Analog Devices ADG792A/G is a triple 4:1 mux.
> >>
> >> Acked-by: Jonathan Cameron <jic23@kernel.org>
> >> Signed-off-by: Peter Rosin <peda@axentia.se>
> >> ---
> >>  .../devicetree/bindings/mux/mux-adg792a.txt        | 79 ++++++++++++++++++++++
> >>  1 file changed, 79 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/mux/mux-adg792a.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/mux/mux-adg792a.txt b/Documentation/devicetree/bindings/mux/mux-adg792a.txt
> >> new file mode 100644
> >> index 000000000000..0b26dd11f070
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/mux/mux-adg792a.txt
> >> @@ -0,0 +1,79 @@
> >> +Bindings for Analog Devices ADG792A/G Triple 4:1 Multiplexers
> >> +
> >> +Required properties:
> >> +- compatible : "adi,adg792a" or "adi,adg792g"
> >> +- #mux-control-cells : <0> if parallel, or <1> if not.
> >> +* Standard mux-controller bindings as decribed in mux-controller.txt

described

> >> +
> >> +Optional properties for ADG792G:
> >> +- gpio-controller : if present, #gpio-cells below is required.
> >> +- #gpio-cells : should be <2>
> >> +			  - First cell is the GPO line number, i.e. 0 or 1
> >> +			  - Second cell is used to specify active high (0)
> >> +			    or active low (1)
> >> +
> >> +Optional properties:
> >> +- adi,parallel : if present, the three muxes are bound together with a single
> >> +  mux controller, controlling all three muxes in parallel.
> > 
> > Can't this be implied by #mux-control-cells == 0?
> 
> Right, good point! I'll drop adi,parallel.
> 
> >> +- adi,idle-state : if present, array of 2-tuples with mux controller number
> >> +  and state that mux controllers will have when idle. States 0 through 3
> >> +  correspond to signals A through D in the datasheet.
> >> +- adi,idle-high-impedance : if present, array of mux controller numbers that
> >> +  should be in the disconnected high-impedance state when idle.
> > 
> > Perhaps combine these 2 to a common idle-state with the index being the 
> > mux controller number and a value of -1 (or 4) being hi-Z.
> 
> At one point [1] I had a straight array for the mux controllers with state 4
> being hi-Z and state 5 being the default "leave mux as-is on release", but
> Jonathan didn't like magic numbers. Can you please read the follow-ups to the
> referenced mail for some background, and then pick out the most suitable color
> for me to paint with? :-)
> 
> [1] https://lkml.org/lkml/2016/11/30/110
> 
> >> +
> >> +Mux controller states 0 through 3 correspond to signals A through D in the
> >> +datasheet. If a mux controller is mentioned in neither adi,idle-state nor

that is already being said under 'adi,idle-state'

> >> +adi,idle-high-impedance it is left in its previously selected state when idle.
> >> +
> >> +Example:
> >> +
> >> +	/*
> >> +	 * Three independent mux controllers (of which one is used).
> >> +	 * Mux 0 is disconnected when idle, mux 1 idles with signal C
> >> +	 * and mux 2 idles with signal A.
> >> +	 */
> >> +	&i2c0 {
> >> +		mux: adg792a@50 {
> > 
> > mux-controller@50
> 
> Yep. Hmm, where have I seen that before? :-)
> 
> Cheers,
> peda
> 
> >> +			compatible = "adi,adg792a";
> >> +			reg = <0x50>;
> >> +			#mux-control-cells = <1>;
> >> +
> >> +			adi,idle-high-impedance = <0>;
> >> +			adi,idle-state = <1 2>, <2 0>;
> >> +		};
> >> +	};
> >> +
> >> +	adc-mux {
> >> +		compatible = "io-channel-mux";
> >> +		io-channels = <&adc 0>;
> >> +		io-channel-names = "parent";
> >> +
> >> +		mux-controls = <&mux 1>;
> >> +
> >> +		channels = "sync-1", "", "out";
> >> +	};
> >> +
> >> +
> >> +	/*
> >> +	 * Three parallel muxes with one mux controller, useful e.g. if
> >> +	 * the adc is differential, thus needing two signals to be muxed
> >> +	 * simultaneously for correct operation.
> >> +	 */
> >> +	&i2c0 {
> >> +		pmux: adg792a@50 {
> >> +			compatible = "adi,adg792a";
> >> +			reg = <0x50>;
> >> +			#mux-control-cells = <0>;
> >> +			adi,parallel;
> >> +		};
> >> +	};
> >> +
> >> +	diff-adc-mux {
> >> +		compatible = "io-channel-mux";
> >> +		io-channels = <&adc 0>;
> >> +		io-channel-names = "parent";
> >> +
> >> +		mux-controls = <&pmux>;
> >> +
> >> +		channels = "sync-1", "", "out";
> >> +	};
> >> -- 
> >> 2.1.4
> >>
> >> --
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> 

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)