HID: magicmouse: disable and add module param for scroll acceleration

Scroll acceleration is unique to the magicmouse driver, and is
unintuitive to a user who is unaware of the functionality. Thus, disable
it by default, but add a module parameter to enable it for power users
who want it.

Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Michael Poole <mdpoole@troilus.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index cd706354496a..4c4a79c760a2 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -30,6 +30,10 @@ static bool emulate_scroll_wheel = true;
 module_param(emulate_scroll_wheel, bool, 0644);
 MODULE_PARM_DESC(emulate_scroll_wheel, "Emulate a scroll wheel");
 
+static bool scroll_acceleration = false;
+module_param(scroll_acceleration, bool, 0644);
+MODULE_PARM_DESC(scroll_acceleration, "Accelerate sequential scroll events");
+
 static bool report_touches = true;
 module_param(report_touches, bool, 0644);
 MODULE_PARM_DESC(report_touches, "Emit touch records (otherwise, only use them for emulation)");
@@ -177,7 +181,9 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
                 switch (tdata[7] & TOUCH_STATE_MASK) {
                 case TOUCH_STATE_START:
                         msc->touches[id].scroll_y = y;
-                        msc->scroll_accel = min_t(int, msc->scroll_accel + 1,
+                        if (scroll_acceleration)
+                                msc->scroll_accel = min_t(int,
+                                                msc->scroll_accel + 1,
                                                 ARRAY_SIZE(accel_profile) - 1);
                         break;
                 case TOUCH_STATE_DRAG: