[PATCH] bcm5974: report ABS_MT_PRESSURE

Report ABS_MT_PRESSURE in the bcm5974 driver with the same data used for
ABS_PRESSURE.

Some touchpad improvements in recent versions of libinput, such as
pressure-based palm detection, will only work if ABS_MT_PRESSURE is
reported.

Signed-off-by: Ryan Hendrickson <redacted>

---

Please treat all of this with an extra grain of salt; this is my first real
foray into both evdev/libinput internals and kernel development. That said,
I have been running this patch on my daily-use MacBookPro5,1 for several
months, so I have reason to believe it's stable. It might not be the
‘right’ way to do this though; I mostly just copied the corresponding code
for ABS_PRESSURE, which from this[1] blog post I've inferred should have
the same values and range.

[1]: http://who-t.blogspot.com/2016/09/understanding-evdev.html

Patch was originally submitted as bug 197909[2], which can be closed if
this is accepted.

[2]: https://bugzilla.kernel.org/show_bug.cgi?id=197909

--- linux-4.13/drivers/input/mouse/bcm5974.c.orig	2017-12-01 

11:36:35.258890243 -0500

+++ linux-4.13/drivers/input/mouse/bcm5974.c	2017-12-01 11:48:55.187342210 
-0500

@@ -548,6 +548,8 @@ static void setup_events_to_report(struc

	 set_abs(input_dev, ABS_MT_POSITION_X, &cfg->x);
	 set_abs(input_dev, ABS_MT_POSITION_Y, &cfg->y);

+	set_abs(input_dev, ABS_MT_PRESSURE, &cfg->p);
+
	 __set_bit(EV_KEY, input_dev->evbit);
	 __set_bit(BTN_LEFT, input_dev->keybit);

@@ -575,10 +577,14 @@ static int report_bt_state(struct bcm597
 	return 0;
 }

-static void report_finger_data(struct input_dev *input, int slot,
+static void report_finger_data(struct input_dev *input,
+			       const struct bcm5974_config *cfg,
+			       int slot,

			        const struct input_mt_pos *pos,
			        const struct tp_finger *f)
{
+	int abs_p;
+
	 input_mt_slot(input, slot);
	 input_mt_report_slot_state(input, MT_TOOL_FINGER, true);

@@ -594,6 +600,9 @@ static void report_finger_data(struct in

	 		 MAX_FINGER_ORIENTATION - raw2int(f->orientation));
	 input_report_abs(input, ABS_MT_POSITION_X, pos->x);
	 input_report_abs(input, ABS_MT_POSITION_Y, pos->y);
+
+	abs_p = clamp_val(256 * raw2int(f->touch_major) / cfg->p.max, 0, 
255);
+	input_report_abs(input, ABS_MT_PRESSURE, abs_p);
 }

static void report_synaptics_data(struct input_dev *input,

@@ -640,7 +649,7 @@ static int report_tp_state(struct bcm597

	 input_mt_assign_slots(input, dev->slots, dev->pos, n, 0);

	for (i = 0; i < n; i++)
-		report_finger_data(input, dev->slots[i],
+		report_finger_data(input, c, dev->slots[i],
				    &dev->pos[i], dev->index[i]);

	input_mt_sync_frame(input);