On 06/12/16 09:18, Peter Rosin wrote: > On 2016-12-06 00:26, Rob Herring wrote: >> On Wed, Nov 30, 2016 at 09:16:58AM +0100, Peter Rosin wrote: >>> Signed-off-by: Peter Rosin <p...@axentia.se> >>> --- >>> .../bindings/iio/multiplexer/iio-mux.txt | 40 >>> ++++++++++++++++++++++ >>> MAINTAINERS | 6 ++++ >>> 2 files changed, 46 insertions(+) >>> create mode 100644 >>> Documentation/devicetree/bindings/iio/multiplexer/iio-mux.txt >> >> I'm still not convinced about this binding, but don't really have more >> comments ATM. Sending 6 versions in 2 weeks or so doesn't really help >> either. > > Sorry about the noise, I'll try to be more careful going forward. On > the flip side, I haven't touched the code since v6. > > I don't see how bindings that are as flexible as the current (and > original) phandle link between the mux consumer and the mux controller > would look, and at the same time be simpler to understand. You need > to be able to refer to a mux controller from several mux consumers, and > you need to support several mux controllers in one node (the ADG792A > case). And, AFAICT, the complex case wasn't really the problem, it was > that it is overly complex to describe the simple case of one mux > consumer and one mux controller. But in your comment for v2 [1] you > said that I was working around limitations with shared GPIO pins. But > solving that in the GPIO subsystem would not solve all that the > phandle approach is solving, since you would not have support for > ADG792A (or other non-GPIO controlled muxes). So, I think listing > the gpio pins inside the mux consumer node is a non-starter, the mux > controller has to live in its own node with its own compatible. > > Would you be happier if I managed to marry the phandle approach with > the option of having the mux controller as a child node of the mux > consumer for the simple case? > > I added an example at the end of this message (the same as the first > example in v4 [2], at least in principle) for easy comparison between > the phandle and the controller-in-child-node approaches. I can't say > that I personally find the difference all that significant, and do not > think it is worth it. As I see it, the "simple option" would just muddy > the waters... > > [1] http://marc.info/?l=linux-kernel&m=147948334204795&w=2 > [2] http://marc.info/?l=linux-kernel&m=148001364904240&w=2 > >>> diff --git a/Documentation/devicetree/bindings/iio/multiplexer/iio-mux.txt >>> b/Documentation/devicetree/bindings/iio/multiplexer/iio-mux.txt >>> new file mode 100644 >>> index 000000000000..8080cf790d82 >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/iio/multiplexer/iio-mux.txt >>> @@ -0,0 +1,40 @@ >>> +IIO multiplexer bindings >>> + >>> +If a multiplexer is used to select which hardware signal is fed to >>> +e.g. an ADC channel, these bindings describe that situation. >>> + >>> +Required properties: >>> +- compatible : "iio-mux" >> >> This is a Linuxism. perhaps "adc-mux". > > No, that's not general enough, it could just as well be used to mux a > temperature sensor. Or whatever. Hmmm, given that "iio-mux" is bad, perhaps > "io-channel-mux" is better? That matches the io-channels property used to > refer to the parent channel. analog-mux maybe? Makes more sense out of context (though with io-channels defined on the next line you have plenty of context here ;) > >>> +- io-channels : Channel node of the parent channel that has multiplexed >>> + input. >>> +- io-channel-names : Should be "parent". >>> +- #address-cells = <1>; >>> +- #size-cells = <0>; >>> +- mux-controls : Mux controller node to use for operating the mux >>> +- channels : List of strings, labeling the mux controller states. >>> + >>> +The multiplexer state as described in ../misc/mux-controller.txt >>> + >>> +For each non-empty string in the channels property, an iio channel will >>> +be created. The number of this iio channel is the same as the index into >>> +the list of strings in the channels property, and also matches the mux >>> +controller state. >>> + >>> +Example: >>> + mux: mux-controller { >>> + compatible = "mux-gpio"; >>> + #mux-control-cells = <0>; >>> + >>> + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, >>> + <&pioA 1 GPIO_ACTIVE_HIGH>; >>> + }; >>> + >>> + adc-mux { >>> + compatible = "iio-mux"; >>> + io-channels = <&adc 0>; >>> + io-channel-names = "parent"; >>> + >>> + mux-controls = <&mux>; >>> + >>> + channels = "sync", "in", system-regulator"; >>> + }; > > Describing the same as above, but with the mux controller as a child > node. > > adc-mux { > compatible = "iio-mux"; > io-channels = <&adc 0>; > io-channel-names = "parent"; > > channels = "sync", "in", system-regulator"; > > mux-controller { > compatible = "mux-gpio"; > > mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, > <&pioA 1 GPIO_ACTIVE_HIGH>; > }; > }; > > Cheers, > Peter > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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