Revert "HID: input: simplify/fix high-res scroll event handling"

This reverts commit 044ee890286153a1aefb40cb8b6659921aecb38b.

It turns out the current API is not that compatible with
some Microsoft mice, so better start again from scratch.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Harry Cutts <hcutts@chromium.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 44ea8e7c71a9c0140f5d69a6f99690a37094649b..28ee2ed88a1aea85491be0acf8ba5a578b415530 100644 (file)
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1858,30 +1858,31 @@ EXPORT_SYMBOL_GPL(hidinput_disconnect);
 void hid_scroll_counter_handle_scroll(struct hid_scroll_counter *counter,
                                      int hi_res_value)
 {
-       int low_res_value, remainder, multiplier;
+       int low_res_scroll_amount;
+       /* Some wheels will rest 7/8ths of a notch from the previous notch
+        * after slow movement, so we want the threshold for low-res events to
+        * be in the middle of the notches (e.g. after 4/8ths) as opposed to on
+        * the notches themselves (8/8ths).
+        */
+       int threshold = counter->resolution_multiplier / 2;
 
        input_report_rel(counter->dev, REL_WHEEL_HI_RES,
                         hi_res_value * counter->microns_per_hi_res_unit);
 
-       /*
-        * Update the low-res remainder with the high-res value,
-        * but reset if the direction has changed.
-        */
-       remainder = counter->remainder;
-       if ((remainder ^ hi_res_value) < 0)
-               remainder = 0;
-       remainder += hi_res_value;
-
-       /*
-        * Then just use the resolution multiplier to see if
-        * we should send a low-res (aka regular wheel) event.
-        */
-       multiplier = counter->resolution_multiplier;
-       low_res_value = remainder / multiplier;
-       remainder -= low_res_value * multiplier;
-       counter->remainder = remainder;
-
-       if (low_res_value)
-               input_report_rel(counter->dev, REL_WHEEL, low_res_value);
+       counter->remainder += hi_res_value;
+       if (abs(counter->remainder) >= threshold) {
+               /* Add (or subtract) 1 because we want to trigger when the wheel
+                * is half-way to the next notch (i.e. scroll 1 notch after a
+                * 1/2 notch movement, 2 notches after a 1 1/2 notch movement,
+                * etc.).
+                */
+               low_res_scroll_amount =
+                       counter->remainder / counter->resolution_multiplier
+                       + (hi_res_value > 0 ? 1 : -1);
+               input_report_rel(counter->dev, REL_WHEEL,
+                                low_res_scroll_amount);
+               counter->remainder -=
+                       low_res_scroll_amount * counter->resolution_multiplier;
+       }
 }
 EXPORT_SYMBOL_GPL(hid_scroll_counter_handle_scroll);