On Tue, Jul 5, 2011 at 1:17 PM, Chase Douglas
[off-list ref] wrote:

On 06/28/2011 10:07 PM, djkurtz@chromium.org wrote:

quoted

From: Daniel Kurtz <redacted>

A Synaptics image sensor tracks 5 fingers, but can only report 2.
This behavior is called "T5R2" = Track 5 Report 2

Algorithm for choosing which 2 fingers to report in which packet:
  Touchpad maintains 5 slots, numbered 0 to 4.
  Initially all slots are empty.
  As new fingers are detected, they are assigned the lowest available
  slot.
  Touchpad always reports:
    SGM: lowest numbered non-empty slot
    AGM: highest numbered non-empty slot, if there is one.

In addition, T5R2 touchpads have a special AGM packet type which reports
the number of fingers currently being tracked, and which finger is in
each of the two slots.  Unfortunately, these "TYPE=2" packets are only used
when more than 3 fingers are being tracked.  When less than 4 fingers
are present, the 'w' value must be used to track how many fingers are
present, and knowing which fingers are being reported is much more
difficult, if not impossible.

Signed-off-by: Daniel Kurtz <redacted>
---
 drivers/input/mouse/synaptics.c |   39 ++++++++++++++++++++++++++++++++++-----
 drivers/input/mouse/synaptics.h |    7 ++++++-
 include/linux/input.h           |    1 +
 3 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 2d7ac0a..19a9b7f 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c

@@ -401,6 +401,14 @@ static void synaptics_pt_create(struct psmouse *psmouse)

 /*****************************************************************************
  *   Functions to interpret the absolute mode packets
  ****************************************************************************/
+/* Set AGM-CONTACT finger state */
+static void synaptics_agm_finger_update(struct synaptics_data *priv, int count,
+                                     int sgm, int agm)
+{
+     priv->agm.finger_count = count;
+     priv->agm.finger_sgm = sgm;
+     priv->agm.finger_agm = agm;
+}

 static int synaptics_parse_hw_state(const unsigned char buf[],
                                  struct synaptics_data *priv,

@@ -438,11 +446,31 @@ static int synaptics_parse_hw_state(const unsigned char buf[],

              if ((SYN_CAP_ADV_GESTURE(priv->ext_cap_0c)
                              || SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c))
                              && hw->w == 2) {
-                     /* Gesture packet: (x, y, z) at half resolution */
-                     priv->agm.x = (((buf[4] & 0x0f) << 8) | buf[1]) << 1;
-                     priv->agm.y = INVERT_Y((((buf[4] & 0xf0) << 4)
-                                           | buf[2]) << 1);
-                     priv->agm.z = ((buf[3] & 0x30) | (buf[5] & 0x0f)) << 1;
+                     int type; /* Packet type */
+
+                     type = (buf[5] & 0x30) >> 4;
+
+                     switch (type) {
+                     case 1:
+                             /* Gesture packet: (x, y, z) half resolution */
+                             priv->agm.w = hw->w;
+                             priv->agm.x = (((buf[4] & 0x0f) << 8)
+                                             | buf[1]) << 1;
+                             priv->agm.y = INVERT_Y((((buf[4] & 0xf0) << 4)
+                                                    | buf[2]) << 1);
+                             priv->agm.z = ((buf[3] & 0x30)
+                                             | (buf[5] & 0x0f)) << 1;
+                             break;
+
+                     case 2:
+                             /* Finger slot update */
+                             synaptics_agm_finger_update(priv, buf[1],
+                                                         buf[2], buf[4]);
+                             break;
+
+                     default:
+                             break;
+                     }
                      return 1;
              } else {
                      hw->x = (((buf[3] & 0x10) << 8) |

@@ -804,6 +832,7 @@ static void set_input_params(struct input_dev *dev, struct synaptics_data *priv)

      input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);

      if (SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)) {
+             __set_bit(INPUT_PROP_SYNAPTICS_T5R2, dev->propbit);
              input_mt_init_slots(dev, SYN_TRACK_SLOT_COUNT);
              input_set_abs_params(dev, ABS_MT_POSITION_X, XMIN_NOMINAL,
                                   priv->x_max ?: XMAX_NOMINAL, fuzz, 0);

diff --git a/drivers/input/mouse/synaptics.h b/drivers/input/mouse/synaptics.h
index 1de2256..2214af6 100644
--- a/drivers/input/mouse/synaptics.h
+++ b/drivers/input/mouse/synaptics.h

@@ -122,7 +122,7 @@

 #define SYN_SLOT_AGM                 2

 /* number of tracking slots for Image Sensor firmware */
-#define SYN_TRACK_SLOT_COUNT         2
+#define SYN_TRACK_SLOT_COUNT         5

 /*
  * A structure to describe the state of the touchpad hardware (buttons and pad)

@@ -140,6 +140,11 @@ struct synaptics_hw_state {

      unsigned int down:1;
      unsigned char ext_buttons;
      signed char scroll;
+
+     /* Reported in AGM-CONTACT packets */
+     unsigned int finger_count;              /* num fingers being tracked */
+     unsigned int finger_sgm;                /* finger described by sgm */
+     unsigned int finger_agm;                /* finger described by agm */
 };

 struct synaptics_data {

diff --git a/include/linux/input.h b/include/linux/input.h
index 771d6d8..732c14e 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h

@@ -137,6 +137,7 @@ struct input_keymap_entry {

 #define INPUT_PROP_DIRECT            0x01    /* direct input devices */
 #define INPUT_PROP_BUTTONPAD         0x02    /* has button(s) under pad */
 #define INPUT_PROP_SEMI_MT           0x03    /* touch rectangle only */
+#define INPUT_PROP_SYNAPTICS_T5R2    0x04    /* synaptics track 5 report 2 */

 #define INPUT_PROP_MAX                       0x1f
 #define INPUT_PROP_CNT                       (INPUT_PROP_MAX + 1)

I'm trying to understand these later patches for T5R2. There are
"hidden" touch slots now. How does userspace tell whether a touch slot
is a hidden touch?

I'm trying to understand as well.  If I was a consumer of events and I
knew touchpad supports 2 touch tracking but 5 finger detection, I'd
assume:

* ABS_X/Y reports oldest touch and
BTN_TOOL_DOUBLETAP/TRIPLETAP/QUADTAP reports # of fingers touching
(ignoring lost of 5 finger for now).
* ABS_MT_* only contains 2 slots and without SEMI_MT declared.
BTN_TOOL_* could be used to detect greater than 2 finger touches.

I'm not sure I could guess what to do with 5 slots and how to expect
touch data to come over them.

Where you saying in the other thread that the 5 slots are to help user
detect finger transitions and re-act bounces in X/Y accordingly?  I'm
assuming they could react in same way to BTN_TOOL_* changes if we can
extend to 5 finger case?

Chris
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