Yes, it's needed.
Even with the same encoder, adjusting steps affects rate of event generation.
(the steps defines 1 cycle of encoder rotation, and 1 cycle = 1 key event.)

On Sun, Jan 6, 2019 at 8:11 AM Dmitry Torokhov
[off-list ref] wrote:

On Sat, Jan 5, 2019 at 2:27 PM Donghoon Han [off-list ref] wrote:

quoted

Add DT binding document for rotary-encoder, keycode options.

Signed-off-by: Donghoon Han <redacted>
---
 .../devicetree/bindings/input/rotary-encoder.txt     | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/rotary-encoder.txt b/Documentation/devicetree/bindings/input/rotary-encoder.txt
index f99fe5cdeaec..113640079de3 100644
--- a/Documentation/devicetree/bindings/input/rotary-encoder.txt
+++ b/Documentation/devicetree/bindings/input/rotary-encoder.txt

@@ -12,6 +12,10 @@ Optional properties:
 - rotary-encoder,relative-axis: register a relative axis rather than an
   absolute one. Relative axis will only generate +1/-1 events on the input
   device, hence no steps need to be passed.
+- rotary-encoder,relative-keys : generate pair of key events. This setting
+  behaves just like relative-axis, generating key events. keycode[2]
+  corresponds -1/1 events.
+- rotary-encoder,relative-keycodes : keycodes for relative-keys
 - rotary-encoder,rollover: Automatic rollover when the rotary value becomes
   greater than the specified steps or smaller than 0. For absolute axis only.
 - rotary-encoder,steps-per-period: Number of steps (stable states) per period.

@@ -48,3 +52,11 @@ Example:
                        rotary-encoder,encoding = "binary";
                        rotary-encoder,rollover;
                };
+
+               rotary@2 {
+                       compatible = "rotary-encoder";
+                       gpios = <&gpio 21 0>, <&gpio 22 0>;
+                       rotary-encoder,relative-keys;
+                       rotary-encoder,relative-keycode = <103>, <108>;
+                       rotary-encoder,steps-per-period = <2>;

Do you need steps for keys? They weren't required for the relative axis mode.

Thanks.

--
Dmitry

-- 
한동훈 드림.