touchpad: ratelimit the touch jump tests

In most cases these days touch jumps aren't actually fixable, they don't have
any good heuristics we can employ to remove them. And, luckily, in most cases
it doesn't matter because the users only notice the issue because of the error
message. To avoid spamming the user's log, let's ratelimit it.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

doc/user/touchpad-jumping-cursors.rst

@@ -14,6 +14,9 @@ position.
 When libinput detects a cursor jump it prints a bug warning to the log with
 the text **"Touch jump detected and discarded."** and a link to this page.
 
+.. note:: This warning is ratelimited and will stop appearing after a few
+	  times, even if the touchpad jumps continue.
+
 In most cases, this is a bug in the kernel driver and to libinput it appears
 that the touch point moves from its previous position. The pointer jump can
 usually be seen in the :ref:`libinput record <libinput-record>` output for the device:

src/evdev-mt-touchpad.c

@@ -1718,10 +1718,11 @@ tp_process_state(struct tp_dispatch *tp, uint64_t time)
 
 		if (tp_detect_jumps(tp, t, time)) {
 			if (!tp->semi_mt)
-				evdev_log_bug_kernel(tp->device,
-					       "Touch jump detected and discarded.\n"
-					       "See %stouchpad-jumping-cursors.html for details\n",
-					       HTTP_DOC_LINK);
+				evdev_log_bug_kernel_ratelimit(tp->device,
+						&tp->jump.warning,
+					        "Touch jump detected and discarded.\n"
+					        "See %stouchpad-jumping-cursors.html for details\n",
+					        HTTP_DOC_LINK);
 			tp_motion_history_reset(t);
 		}
 
@@ -3581,6 +3582,9 @@ tp_init(struct tp_dispatch *tp,
 	if (!use_touch_size)
 		tp_init_pressure(tp, device);
 
+	/* 5 warnings per 2 hours should be enough */
+	ratelimit_init(&tp->jump.warning, s2us(2 * 60 * 60), 5);
+
 	/* Set the dpi to that of the x axis, because that's what we normalize
 	   to when needed*/
 	device->dpi = device->abs.absinfo_x->resolution * 25.4;

src/evdev-mt-touchpad.h

@@ -279,6 +279,10 @@ struct tp_dispatch {
 	 */
 	unsigned int fake_touches;
 
+	struct {
+		struct ratelimit warning;
+	} jump;
+
 	/* if pressure goes above high -> touch down,
 	   if pressure then goes below low -> touch up */
 	struct {