[PATCH RFC 0/3] input: rotary_encoder: use more than two gpios as input

Uwe Kleine-König u.kleine-koenig at pengutronix.de
Wed Dec 2 02:07:11 PST 2015


some time ago I worked on the rotary encoder driver to make it support
more than two input lines. This is the (only slightly tested[1]) rebase of
this series on top of 4.4-rc2 (from 4.1).

It would be great to get some feedback, especially (but not only) for my
change to raumfeld.c.

Before Ezequiel's patch 3a341a4c30d4 ("Input: rotary-encoder - add
support for quarter-period mode") we had a dt property
"rotary-encoder,half-period" defined. It's presence meant that we had 2
indents per period; it's absence that there is only 1. Ezequiel
introduced rotary-encoder,steps-per-period instead when adding support
for quarter-period mode (which has 4 indents per period).

Up to now (i.e. with two inputs) a period has length 4. Now with (say)
four inputs a period has length 16 instead. Now how should this be
modeled in dt? This series implements that I have to pass

	rotary-encoder,steps-per-period = <16>;

now for "quarter-period mode" (i.e. 4 indents per 4 state changes[2]),
but that feels unnatural. I'd prefer to set a property to <1> instead,
meaning the device has an indent for each state change[2]. half-period
mode would be <2> and full-period mode would be <4>. But I don't have a
nice name for such a property and maybe it's easier to live with
steps-per-period = <16>? What do you think?

Also note that these patches are not as technically versatile as
possible. With 4 (n) input lines we could detect a quick rotation where the
machine's latency only allows to sample after 7 (2^(n-1)-1) state
changes. Currently this is not implemented, but can be done later.

Best regards

[1] the machine that has the device is ~600 km away from me
[2] if you have a better word for that, please tell me.

Uwe Kleine-König (3):
  input: rotary_encoder: make use of devm_* to simplify .probe and
  input: rotary_encoder: move configuration data to driver data
  input: rotary_encoder: support more than 2 gpios as input

 .../devicetree/bindings/input/rotary-encoder.txt   |   2 +-
 arch/arm/mach-pxa/raumfeld.c                       |  25 +-
 drivers/input/misc/rotary_encoder.c                | 283 ++++++++++-----------
 include/linux/rotary_encoder.h                     |   4 -
 4 files changed, 153 insertions(+), 161 deletions(-)


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