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authorEzequiel Garcia <ezequiel@vanguardiasur.com.ar>2015-10-13 23:39:50 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2015-10-16 15:32:18 -0700
commit3a341a4c30d427fd05617087db1564a595f65093 (patch)
tree84898e187b5128e1e51e9f5ed41114176181b71e /Documentation/input
parent648b15cb79e90d80f7b53d0184bdb14132a03754 (diff)
downloadlinux-3a341a4c30d427fd05617087db1564a595f65093.tar.bz2
Input: rotary-encoder - add support for quarter-period mode
Some encoders have both outputs low in stable states, others also have a stable state with both outputs high (half-period mode) and some have a stable state in all steps (quarter-period mode). The driver used to support the former states and with this change it can also support the later. This commit also deprecates the 'half-period' property and introduces a new property 'steps-per-period'. This property specifies the number of steps (stable states) produced by the rotary encoder for each GPIO period. Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/input')
-rw-r--r--Documentation/input/rotary-encoder.txt8
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
index bddbee188624..46a74f0c551a 100644
--- a/Documentation/input/rotary-encoder.txt
+++ b/Documentation/input/rotary-encoder.txt
@@ -9,8 +9,9 @@ peripherals with two wires. The outputs are phase-shifted by 90 degrees
and by triggering on falling and rising edges, the turn direction can
be determined.
-Some encoders have both outputs low in stable states, whereas others also have
-a stable state with both outputs high (half-period mode).
+Some encoders have both outputs low in stable states, others also have
+a stable state with both outputs high (half-period mode) and some have
+a stable state in all steps (quarter-period mode).
The phase diagram of these two outputs look like this:
@@ -32,6 +33,9 @@ The phase diagram of these two outputs look like this:
|<-->|
one step (half-period mode)
+ |<>|
+ one step (quarter-period mode)
+
For more information, please see
https://en.wikipedia.org/wiki/Rotary_encoder