Re: properties to describe a rotary encoder

[Daniel Mack <daniel-cYrQPVfZoowdnm+yROfE0A@public.gmane.org>]

Hi,

On 10/16/2015 11:59 AM, Uwe Kleine-König wrote:
> there is already a driver for rotary encoders described in
> Documentation/devicetree/bindings/input/rotary-encoder.txt. This however
> is not suitable to describe the device I have here for two reasons:
> 
> First the driver can only make use of 2 gpio lines, while the device
> here has 4 lines,

How does the phase diagram of that device look like, on what edges is
the system supposed to trigger?

> so I have 16 sectors instead of only 4. And the

What's a 'sector'?

> second difference is that my encoder has a detend for each sector while
> the driver only supports "half-period" and "full-period" (default) mode.
> These names really only make sense for the 2 line case and mean the
> encoder has detends in 2 or 1 sector respectively.
> 
> So I'm thinking about how to generalize the description to allow to add
> support for "my" device.
> 
> For the added gpio lines it's easy, that's just allowing more than two
> gpios for the "gpios" property.

Doesn't the number of GPIOs already give enough information to implement
proper support? Maybe there's no need for any other properties here.

> Currently there is a property "rotary-encoder,steps" that describes the
> number of detends in a full turnaround. So if we stick to "steps" to
> describe detends, maybe something like "sectors-per-step" (with a
> default of 4) would be needed to describe what "half-period" is now.
> Does this make sense? Maybe someone has a better suggestion?

I'm not sure what a sector is supposed to refer to, but the number of
steps per 360° is something that can vary for both 2-line and 4-line
versions of a rotary encoder. So isn't that unrelated?


Thanks,
Daniel

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