Input: Add the REL_WHEEL_HI_RES event code

This event code represents scroll reports from high-resolution wheels, and will be used by future patches in this series. See the linux-input "Reporting high-resolution scroll events" thread [0] for more details. [0]: https://www.spinics.net/lists/linux-input/msg57380.html Signed-off-by: Harry Cutts <[email protected]> Acked-by: Dmitry Torokhov <[email protected]> Reviewed-by: Benjamin Tissoires <[email protected]> Signed-off-by: Jiri Kosina <[email protected]>
ambv · Sep 5, 2018 · aaf9978 · aaf9978
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diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst
@@ -190,7 +190,16 @@ A few EV_REL codes have special meanings:
 * REL_WHEEL, REL_HWHEEL:
 
   - These codes are used for vertical and horizontal scroll wheels,
-    respectively.
+    respectively. The value is the number of "notches" moved on the wheel, the
+    physical size of which varies by device. For high-resolution wheels (which
+    report multiple events for each notch of movement, or do not have notches)
+    this may be an approximation based on the high-resolution scroll events.
+
+* REL_WHEEL_HI_RES:
+
+  - If a vertical scroll wheel supports high-resolution scrolling, this code
+    will be emitted in addition to REL_WHEEL. The value is the (approximate)
+    distance travelled by the user's finger, in microns.
 
 EV_ABS
 ------

diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h
@@ -708,6 +708,7 @@
 #define REL_DIAL		0x07
 #define REL_WHEEL		0x08
 #define REL_MISC		0x09
+#define REL_WHEEL_HI_RES	0x0a
 #define REL_MAX			0x0f
 #define REL_CNT			(REL_MAX+1)