[PATCH v4] Input: synaptics - use firmware data for Cr-48

[PATCH v4] Input: synaptics - use firmware data for Cr-48

[Chung-yih Wang]

The profile sensor clickpad in a Cr-48 Chromebook does a reasonable job of
tracking individual fingers. This tracking isn't perfect, but, experiments
show that it works better than just passing "semi-mt" data to userspace,
and making userspace try to deduce where the fingers are given a bounding box.

This patch tries to report two-finger positions directly from firmware's sgm
and agm packets instead of the {(min_x, min_y), (max_x, max_y)} for profile
sensor clickpads on Cr-48 chromebooks. Note that this device's firmware always
reports the higher (smaller y) finger in the "sgm" packet, and the lower
(larger y) finger in the "agm" packet for the state transition from one finger
to two finger. Then the firmware keeps tracking of fingers with the same agm
or sgm packets individually. Thus, when a new finger arrives on the pad, the
kernel driver uses a simple Euclidean distance measure to deduce which of the
two new fingers should keep the tracking ID of the previous single finger.
Similarly, when one finger is removed, the same measure is used to determine
which finger remained on the pad.

Signed-off-by: Chung-yih Wang <cywang@chromium.org>
---
 drivers/input/mouse/synaptics.c | 95 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 2f78538..ee39842 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -67,6 +67,8 @@
 #define X_MAX_POSITIVE 8176
 #define Y_MAX_POSITIVE 8176
 
+static bool cr48_profile_sensor;
+
 /*****************************************************************************
  *	Stuff we need even when we do not want native Synaptics support
  ****************************************************************************/
@@ -1064,6 +1066,77 @@ static void synaptics_image_sensor_process(struct psmouse *psmouse,
 	priv->agm_pending = false;
 }
 
+static int synaptics_distsq(const struct input_mt_slot *slot,
+			    const struct synaptics_hw_state *hw)
+{
+	int slot_x = input_mt_get_value(slot, ABS_MT_POSITION_X);
+	int slot_y = input_mt_get_value(slot, ABS_MT_POSITION_Y);
+	int dx = hw->x - slot_x;
+	int dy = synaptics_invert_y(hw->y) - slot_y;
+	return dx * dx + dy * dy;
+}
+
+static bool synaptics_is_sgm_slot(const struct input_mt_slot *slot,
+				  const struct synaptics_hw_state *sgm,
+				  const struct synaptics_hw_state *agm)
+{
+	return (synaptics_distsq(slot, sgm) < synaptics_distsq(slot, agm));
+}
+
+static int synaptics_get_sgm_slot(const struct input_mt_slot *slots,
+				  const struct synaptics_hw_state *sgm)
+{
+	int distsq_slot0 = synaptics_distsq(&slots[0], sgm);
+	int distsq_slot1 = synaptics_distsq(&slots[1], sgm);
+	return (distsq_slot0 < distsq_slot1 ? 0 : 1);
+}
+
+static void synaptics_profile_sensor_process(struct psmouse *psmouse,
+					     struct synaptics_hw_state *sgm,
+					     int num_fingers)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct synaptics_data *priv = psmouse->private;
+	struct synaptics_hw_state *agm = &priv->agm;
+	struct synaptics_mt_state mt_state;
+
+	/* Initialize using current mt_state (as updated by last agm) */
+	mt_state = agm->mt_state;
+
+	if (num_fingers >= 2) {
+		/* Get previous sgm slot if exists */
+		int sgm_slot = (mt_state.count != 0) ? mt_state.sgm : 0;
+		if (mt_state.count == 1) {
+			const struct input_mt_slot *mt = &dev->mt[sgm_slot];
+			if (!synaptics_is_sgm_slot(mt, sgm, agm))
+				sgm_slot = 1 - sgm_slot;
+		}
+		synaptics_report_slot(dev, sgm_slot, sgm);
+		synaptics_report_slot(dev, 1 - sgm_slot, agm);
+		synaptics_mt_state_set(&mt_state, num_fingers,
+				       sgm_slot, 1 - sgm_slot);
+	} else if (num_fingers == 1) {
+		int sgm_slot = (mt_state.count != 0) ? mt_state.sgm : 0;
+		if (mt_state.count >= 2)
+			sgm_slot = synaptics_get_sgm_slot(dev->mt, sgm);
+		synaptics_report_slot(dev, sgm_slot, sgm);
+		synaptics_report_slot(dev, 1 - sgm_slot, NULL);
+		synaptics_mt_state_set(&mt_state, 1, sgm_slot, -1);
+	} else {
+		synaptics_report_slot(dev, 0, NULL);
+		synaptics_report_slot(dev, 1, NULL);
+		synaptics_mt_state_set(&mt_state, 0, -1, -1);
+	}
+	/* Store updated mt_state */
+	priv->mt_state = agm->mt_state = mt_state;
+
+	input_mt_report_pointer_emulation(dev, false);
+	/* Send the number of fingers reported by touchpad itself. */
+	input_mt_report_finger_count(dev, mt_state.count);
+	synaptics_report_buttons(psmouse, sgm);
+	input_sync(dev);
+}
+
 /*
  *  called for each full received packet from the touchpad
  */
@@ -1127,6 +1200,11 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 		finger_width = 0;
 	}
 
+	if (cr48_profile_sensor) {
+		synaptics_profile_sensor_process(psmouse, &hw, num_fingers);
+		return;
+	}
+
 	if (SYN_CAP_ADV_GESTURE(priv->ext_cap_0c))
 		synaptics_report_semi_mt_data(dev, &hw, &priv->agm,
 					      num_fingers);
@@ -1288,6 +1366,9 @@ static void set_input_params(struct input_dev *dev, struct synaptics_data *priv)
 					ABS_MT_POSITION_Y);
 	}
 
+	if (cr48_profile_sensor)
+		input_set_abs_params(dev, ABS_MT_PRESSURE, 0, 255, 0, 0);
+
 	if (SYN_CAP_PALMDETECT(priv->capabilities))
 		input_set_abs_params(dev, ABS_TOOL_WIDTH, 0, 15, 0, 0);
 
@@ -1483,10 +1564,24 @@ static const struct dmi_system_id __initconst olpc_dmi_table[] = {
 	{ }
 };
 
+static const struct dmi_system_id __initconst cr48_dmi_table[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Cr-48 Chromebook (Codename Mario) */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IEC"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Mario"),
+		},
+	},
+#endif
+	{ }
+};
+
 void __init synaptics_module_init(void)
 {
 	impaired_toshiba_kbc = dmi_check_system(toshiba_dmi_table);
 	broken_olpc_ec = dmi_check_system(olpc_dmi_table);
+	cr48_profile_sensor = dmi_check_system(cr48_dmi_table);
 }
 
 static int __synaptics_init(struct psmouse *psmouse, bool absolute_mode)
-- 
1.8.1.3

Re: [PATCH v4] Input: synaptics - use firmware data for Cr-48

[Henrik Rydberg]

Hi Chung-yih,

> The profile sensor clickpad in a Cr-48 Chromebook does a reasonable job of
> tracking individual fingers. This tracking isn't perfect, but, experiments
> show that it works better than just passing "semi-mt" data to userspace,
> and making userspace try to deduce where the fingers are given a bounding box.
> 
> This patch tries to report two-finger positions directly from firmware's sgm
> and agm packets instead of the {(min_x, min_y), (max_x, max_y)} for profile
> sensor clickpads on Cr-48 chromebooks. Note that this device's firmware always
> reports the higher (smaller y) finger in the "sgm" packet, and the lower
> (larger y) finger in the "agm" packet for the state transition from one finger
> to two finger. Then the firmware keeps tracking of fingers with the same agm
> or sgm packets individually. Thus, when a new finger arrives on the pad, the
> kernel driver uses a simple Euclidean distance measure to deduce which of the
> two new fingers should keep the tracking ID of the previous single finger.
> Similarly, when one finger is removed, the same measure is used to determine
> which finger remained on the pad.
> 
> Signed-off-by: Chung-yih Wang <cywang@chromium.org>
> ---
>  drivers/input/mouse/synaptics.c | 95 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 95 insertions(+)

I looks right per se, but the procedure is a bit more manual than it
needs to be.  The input core can handle slot allocation these days, so
I wonder if the the two patches below work for you, as an
alternative?

Thanks,
Henrik

---

>From 47629b43c260cb9c1ccbd5c474d89da81a029d27 Mon Sep 17 00:00:00 2001
From: Henrik Rydberg <rydberg@euromail.se>
Date: Wed, 20 Feb 2013 22:36:52 +0100
Subject: [PATCH 1/2] Input: MT - Make slot cleanup callable outside
 mt_sync_frame()

Some semi-mt drivers use the slots in a manual way, but may still
want to call parts of the frame synchronization logic. This patch
makes input_mt_drop_unused callable from those drivers.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
 drivers/input/input-mt.c | 38 +++++++++++++++++++++++++++-----------
 include/linux/input/mt.h |  1 +
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index 1b7f4d4..a22094d 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -235,6 +235,31 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 EXPORT_SYMBOL(input_mt_report_pointer_emulation);
 
 /**
+ * input_mt_drop_unused() - Inactivate slots not seen in this frame
+ * @dev: input device with allocated MT slots
+ *
+ * Lift all slots not seen since the last call to this function.
+ */
+void input_mt_drop_unused(struct input_dev *dev)
+{
+	struct input_mt *mt = dev->mt;
+	struct input_mt_slot *s;
+
+	if (!mt)
+		return;
+
+	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
+		if (s->frame == mt->frame)
+			continue;
+		input_mt_slot(dev, s - mt->slots);
+		input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
+	}
+
+	mt->frame++;
+}
+EXPORT_SYMBOL(input_mt_drop_unused);
+
+/**
  * input_mt_sync_frame() - synchronize mt frame
  * @dev: input device with allocated MT slots
  *
@@ -245,23 +270,14 @@ EXPORT_SYMBOL(input_mt_report_pointer_emulation);
 void input_mt_sync_frame(struct input_dev *dev)
 {
 	struct input_mt *mt = dev->mt;
-	struct input_mt_slot *s;
 
 	if (!mt)
 		return;
 
-	if (mt->flags & INPUT_MT_DROP_UNUSED) {
-		for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
-			if (s->frame == mt->frame)
-				continue;
-			input_mt_slot(dev, s - mt->slots);
-			input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
-		}
-	}
+	if (mt->flags & INPUT_MT_DROP_UNUSED)
+		input_mt_drop_unused(dev);
 
 	input_mt_report_pointer_emulation(dev, (mt->flags & INPUT_MT_POINTER));
-
-	mt->frame++;
 }
 EXPORT_SYMBOL(input_mt_sync_frame);
 
diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index cc5cca7..5766be1 100644
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -98,6 +98,7 @@ void input_mt_report_slot_state(struct input_dev *dev,
 
 void input_mt_report_finger_count(struct input_dev *dev, int count);
 void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count);
+void input_mt_drop_unused(struct input_dev *dev);
 
 void input_mt_sync_frame(struct input_dev *dev);
 
-- 
1.8.1.3

>From 62a7bca6a782e83736c782c0b91e8640f2e5a140 Mon Sep 17 00:00:00 2001
From: Henrik Rydberg <rydberg@euromail.se>
Date: Wed, 20 Feb 2013 22:47:18 +0100
Subject: [PATCH 2/2] Input: synaptics - Alternative use of firmware data for
 Cr-48

---
 drivers/input/mouse/synaptics.c | 60 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index a8590ad..52b30ad 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -67,6 +67,8 @@
 #define X_MAX_POSITIVE 8176
 #define Y_MAX_POSITIVE 8176
 
+static bool cr48_profile_sensor;
+
 /*****************************************************************************
  *	Stuff we need even when we do not want native Synaptics support
  ****************************************************************************/
@@ -1040,6 +1042,42 @@ static void synaptics_image_sensor_process(struct psmouse *psmouse,
 	priv->agm_pending = false;
 }
 
+static void synaptics_profile_sensor_process(struct psmouse *psmouse,
+					     struct synaptics_hw_state *sgm,
+					     int num_fingers)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct synaptics_data *priv = psmouse->private;
+	struct synaptics_hw_state *hw[2] = { sgm, &priv->agm };
+	struct input_mt_pos pos[2];
+	int slot[2], nsemi, i;
+
+	nsemi = clamp_val(num_fingers, 0, 2);
+
+	for (i = 0; i < nsemi; i++) {
+		pos[i].x = hw[i]->x;
+		pos[i].y = synaptics_invert_y(hw[i]->y);
+	}
+
+	input_mt_assign_slots(dev, slot, pos, nsemi);
+
+	for (i = 0; i < nsemi; i++) {
+		input_mt_slot(dev, slot[i]);
+		input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);
+		input_report_abs(dev, ABS_MT_POSITION_X, pos[i].x);
+		input_report_abs(dev, ABS_MT_POSITION_Y, pos[i].y);
+		input_report_abs(dev, ABS_MT_PRESSURE, hw[i]->z);
+	}
+
+	input_mt_drop_unused(dev);
+	input_mt_report_pointer_emulation(dev, false);
+	input_mt_report_finger_count(dev, num_fingers);
+
+	synaptics_report_buttons(psmouse, sgm);
+
+	input_sync(dev);
+}
+
 /*
  *  called for each full received packet from the touchpad
  */
@@ -1103,6 +1141,11 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 		finger_width = 0;
 	}
 
+	if (cr48_profile_sensor) {
+		synaptics_profile_sensor_process(psmouse, &hw, num_fingers);
+		return;
+	}
+
 	if (SYN_CAP_ADV_GESTURE(priv->ext_cap_0c))
 		synaptics_report_semi_mt_data(dev, &hw, &priv->agm,
 					      num_fingers);
@@ -1246,6 +1289,9 @@ static void set_input_params(struct input_dev *dev, struct synaptics_data *priv)
 	set_abs_position_params(dev, priv, ABS_X, ABS_Y);
 	input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);
 
+	if (cr48_profile_sensor)
+		input_set_abs_params(dev, ABS_MT_PRESSURE, 0, 255, 0, 0);
+
 	if (SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)) {
 		set_abs_position_params(dev, priv, ABS_MT_POSITION_X,
 					ABS_MT_POSITION_Y);
@@ -1459,10 +1505,24 @@ static const struct dmi_system_id __initconst olpc_dmi_table[] = {
 	{ }
 };
 
+static const struct dmi_system_id __initconst cr48_dmi_table[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Cr-48 Chromebook (Codename Mario) */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IEC"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Mario"),
+		},
+	},
+#endif
+	{ }
+};
+
 void __init synaptics_module_init(void)
 {
 	impaired_toshiba_kbc = dmi_check_system(toshiba_dmi_table);
 	broken_olpc_ec = dmi_check_system(olpc_dmi_table);
+	cr48_profile_sensor = dmi_check_system(cr48_dmi_table);
 }
 
 static int __synaptics_init(struct psmouse *psmouse, bool absolute_mode)
-- 
1.8.1.3

Re: [PATCH v4] Input: synaptics - use firmware data for Cr-48

[Dmitry Torokhov]

Hi Henrik,

On Wed, Feb 20, 2013 at 10:55:13PM +0100, Henrik Rydberg wrote:
> Hi Chung-yih,
> 
> > The profile sensor clickpad in a Cr-48 Chromebook does a reasonable job of
> > tracking individual fingers. This tracking isn't perfect, but, experiments
> > show that it works better than just passing "semi-mt" data to userspace,
> > and making userspace try to deduce where the fingers are given a bounding box.
> > 
> > This patch tries to report two-finger positions directly from firmware's sgm
> > and agm packets instead of the {(min_x, min_y), (max_x, max_y)} for profile
> > sensor clickpads on Cr-48 chromebooks. Note that this device's firmware always
> > reports the higher (smaller y) finger in the "sgm" packet, and the lower
> > (larger y) finger in the "agm" packet for the state transition from one finger
> > to two finger. Then the firmware keeps tracking of fingers with the same agm
> > or sgm packets individually. Thus, when a new finger arrives on the pad, the
> > kernel driver uses a simple Euclidean distance measure to deduce which of the
> > two new fingers should keep the tracking ID of the previous single finger.
> > Similarly, when one finger is removed, the same measure is used to determine
> > which finger remained on the pad.
> > 
> > Signed-off-by: Chung-yih Wang <cywang@chromium.org>
> > ---
> >  drivers/input/mouse/synaptics.c | 95 +++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 95 insertions(+)
> 
> I looks right per se, but the procedure is a bit more manual than it
> needs to be.  The input core can handle slot allocation these days, so
> I wonder if the the two patches below work for you, as an
> alternative?

You forgot to tell input_mt_init_slots() to track the contacts, but
otherwise it works. The version of the patch below seems to work well on
Cr-48 for me.

Thanks.

-- 
Dmitry


Input: synaptics - use firmware data for Cr-48

From: Henrik Rydberg <rydberg@euromail.se>

The profile sensor clickpad in a Cr-48 Chromebook does a reasonable job
of tracking individual fingers. This tracking isn't perfect, but,
experiments show that it works better than just passing "semi-mt" data
to userspace, and making userspace try to deduce where the fingers are
given a bounding box.

This patch tries to report correct two-finger positions instead of the
{(min_x, min_y), (max_x, max_y)} for profile sensor clickpads on Cr-48
chromebooks. Note that this device's firmware always reports the higher
(smaller y) finger in the "sgm" packet, and the lower (larger y) finger
in the "agm" packet. Thus, when a new finger arrives on the pad, the
kernel driver uses input core's contact tracking facilities to match
contacts with slots.

Inspired by patch by Daniel Kurtz <djkurtz@chromium.org> and Chung-yih
Wang <cywang@chromium.org>

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/mouse/synaptics.c |   69 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index fe607e9..f261db9 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -67,6 +67,8 @@
 #define X_MAX_POSITIVE 8176
 #define Y_MAX_POSITIVE 8176
 
+static bool cr48_profile_sensor;
+
 /*****************************************************************************
  *	Stuff we need even when we do not want native Synaptics support
  ****************************************************************************/
@@ -1152,6 +1154,42 @@ static void synaptics_image_sensor_process(struct psmouse *psmouse,
 	priv->agm_pending = false;
 }
 
+static void synaptics_profile_sensor_process(struct psmouse *psmouse,
+					     struct synaptics_hw_state *sgm,
+					     int num_fingers)
+{
+	struct input_dev *dev = psmouse->dev;
+	struct synaptics_data *priv = psmouse->private;
+	struct synaptics_hw_state *hw[2] = { sgm, &priv->agm };
+	struct input_mt_pos pos[2];
+	int slot[2], nsemi, i;
+
+	nsemi = clamp_val(num_fingers, 0, 2);
+
+	for (i = 0; i < nsemi; i++) {
+		pos[i].x = hw[i]->x;
+		pos[i].y = synaptics_invert_y(hw[i]->y);
+	}
+
+	input_mt_assign_slots(dev, slot, pos, nsemi);
+
+	for (i = 0; i < nsemi; i++) {
+		input_mt_slot(dev, slot[i]);
+		input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);
+		input_report_abs(dev, ABS_MT_POSITION_X, pos[i].x);
+		input_report_abs(dev, ABS_MT_POSITION_Y, pos[i].y);
+		input_report_abs(dev, ABS_MT_PRESSURE, hw[i]->z);
+	}
+
+	input_mt_drop_unused(dev);
+	input_mt_report_pointer_emulation(dev, false);
+	input_mt_report_finger_count(dev, num_fingers);
+
+	synaptics_report_buttons(psmouse, sgm);
+
+	input_sync(dev);
+}
+
 /*
  *  called for each full received packet from the touchpad
  */
@@ -1215,6 +1253,11 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 		finger_width = 0;
 	}
 
+	if (cr48_profile_sensor) {
+		synaptics_profile_sensor_process(psmouse, &hw, num_fingers);
+		return;
+	}
+
 	if (SYN_CAP_ADV_GESTURE(priv->ext_cap_0c))
 		synaptics_report_semi_mt_data(dev, &hw, &priv->agm,
 					      num_fingers);
@@ -1360,6 +1403,9 @@ static void set_input_params(struct psmouse *psmouse,
 	set_abs_position_params(dev, priv, ABS_X, ABS_Y);
 	input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);
 
+	if (cr48_profile_sensor)
+		input_set_abs_params(dev, ABS_MT_PRESSURE, 0, 255, 0, 0);
+
 	if (SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)) {
 		set_abs_position_params(dev, priv, ABS_MT_POSITION_X,
 					ABS_MT_POSITION_Y);
@@ -1373,9 +1419,14 @@ static void set_input_params(struct psmouse *psmouse,
 	} else if (SYN_CAP_ADV_GESTURE(priv->ext_cap_0c)) {
 		set_abs_position_params(dev, priv, ABS_MT_POSITION_X,
 					ABS_MT_POSITION_Y);
-		/* Non-image sensors with AGM use semi-mt */
+		/*
+		 * Profile sensor in CR-48 tracks contacts reasonably well,
+		 * other non-image sensors with AGM use semi-mt.
+		 */
 		input_mt_init_slots(dev, 2,
-				    INPUT_MT_POINTER | INPUT_MT_SEMI_MT);
+				    INPUT_MT_POINTER |
+				    (cr48_profile_sensor ?
+					INPUT_MT_TRACK : INPUT_MT_SEMI_MT));
 	}
 
 	if (SYN_CAP_PALMDETECT(priv->capabilities))
@@ -1577,10 +1628,24 @@ static const struct dmi_system_id olpc_dmi_table[] __initconst = {
 	{ }
 };
 
+static const struct dmi_system_id __initconst cr48_dmi_table[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Cr-48 Chromebook (Codename Mario) */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IEC"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Mario"),
+		},
+	},
+#endif
+	{ }
+};
+
 void __init synaptics_module_init(void)
 {
 	impaired_toshiba_kbc = dmi_check_system(toshiba_dmi_table);
 	broken_olpc_ec = dmi_check_system(olpc_dmi_table);
+	cr48_profile_sensor = dmi_check_system(cr48_dmi_table);
 }
 
 static int __synaptics_init(struct psmouse *psmouse, bool absolute_mode)