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Input: synaptics - process finger (<=3) transitions

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Synaptics image sensor touchpads track 5 fingers, but only report 2.
This patch attempts to deal with some idiosyncrasies of these touchpads:

 * When there are 3 or more fingers, only two are reported.
 * The touchpad tracks the 5 fingers in slot[0] through slot[4].
 * It always reports the lowest and highest valid slots in SGM and AGM
   packets, respectively.
 * The number of fingers is only reported in the SGM packet.  However,
   the number of fingers can change either before or after an AGM
   packet.
 * Thus, if an SGM reports a different number of fingers than the last
   SGM, it is impossible to tell whether the intervening AGM corresponds
   to the old number of fingers or the new number of fingers.
 * For example, when going from 2->3 fingers, it is not possible to tell
   whether tell AGM contains slot[1] (old 2nd finger) or slot[2] (new
   3rd finger).
 * When fingers are added one at at time, from 1->2->3, it is possible to
   track which slots are contained in the SGM and AGM packets:
     1 finger:  SGM = slot[0], no AGM
     2 fingers: SGM = slot[0], AGM = slot[1]
     3 fingers: SGM = slot[0], AGM = slot[2]
 * It is also possible to track which slot is contained in the SGM when 1
   of 2 fingers is removed.  This is because the touchpad sends a special
   (0,0,0) AGM packet whenever all fingers are removed except slot[0]:
     Last AGM == (0,0,0): SGM contains slot[1]
     Else: SGM contains slot[0]
 * However, once there are 3 fingers, if exactly 1 finger is removed, it
   is impossible to tell which 2 slots are contained in SGM and AGM.
   The (SGM,AGM) could be (0,1), (0,2), or (1,2). There is no way to know.
 * Similarly, if two fingers are simultaneously removed (3->1), then it
   is only possible to know if SGM still contains slot[0].
 * Since it is not possible to reliably track which slot is being
   reported, we invalidate the tracking_id every time the number of
   fingers changes until this ambiguity is resolved when:
     a) All fingers are removed.
     b) 4 or 5 fingers are touched, generates an AGM-CONTACT packet.
     c) All fingers are removed except slot[0].  In this special case, the
        ambiguity is resolved since by the (0,0,0) AGM packet.

Behavior of the driver:

When 2 or more fingers are present on the touchpad, the kernel reports
up to two MT-B slots containing the position data for two of the fingers
reported by the touchpad.  If the identity of a finger cannot be tracked
when the number-of-fingers changes, the corresponding MT-B slot will be
invalidated (track_id set to -1), and a new track_id will be assigned in
a subsequent input event report.

The driver always reports the total number of fingers using one of the
EV_KEY/BTN_TOOL_*TAP events. This could differ from the number of valid
MT-B slots for two reasons:
 a) There are more than 2 fingers on the pad.
 b) During ambiguous number-of-fingers transitions, the correct track_id
    for one or both of the slots cannot be determined, so the slots are
    invalidated.

Thus, this is a hybrid singletouch/MT-B scheme. Userspace can detect
this behavior by noting that the driver supports more EV_KEY/BTN_TOOL_*TAP
events than its maximum EV_ABS/ABS_MT_SLOT.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Acked-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Daniel Kurtz 2011-08-23 23:02:40 -07:00 committed by Dmitry Torokhov
parent a93bd154d8
commit 4dc772d274
2 changed files with 278 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

290
drivers/input/mouse/synaptics.c
View file

@ -453,6 +453,9 @@ static void synaptics_parse_agm(const unsigned char buf[],
default:
break;
}
/* Record that at least one AGM has been received since last SGM */
priv->agm_pending = true;
}
static int synaptics_parse_hw_state(const unsigned char buf[],
@ -606,26 +609,53 @@ static void synaptics_report_slot(struct input_dev *dev, int slot,
}
static void synaptics_report_mt_data(struct psmouse *psmouse,
int count,
struct synaptics_mt_state *mt_state,
const struct synaptics_hw_state *sgm)
{
struct input_dev *dev = psmouse->dev;
struct synaptics_data *priv = psmouse->private;
struct synaptics_hw_state *agm = &priv->agm;
struct synaptics_mt_state *old = &priv->mt_state;
switch (count) {
switch (mt_state->count) {
case 0:
synaptics_report_slot(dev, 0, NULL);
synaptics_report_slot(dev, 1, NULL);
break;
case 1:
synaptics_report_slot(dev, 0, sgm);
synaptics_report_slot(dev, 1, NULL);
if (mt_state->sgm == -1) {
synaptics_report_slot(dev, 0, NULL);
synaptics_report_slot(dev, 1, NULL);
} else if (mt_state->sgm == 0) {
synaptics_report_slot(dev, 0, sgm);
synaptics_report_slot(dev, 1, NULL);
} else {
synaptics_report_slot(dev, 0, NULL);
synaptics_report_slot(dev, 1, sgm);
}
break;
case 2:
case 3: /* Fall-through case */
synaptics_report_slot(dev, 0, sgm);
synaptics_report_slot(dev, 1, agm);
default:
/*
* If the finger slot contained in SGM is valid, and either
* hasn't changed, or is new, then report SGM in MTB slot 0.
* Otherwise, empty MTB slot 0.
*/
if (mt_state->sgm != -1 &&
(mt_state->sgm == old->sgm || old->sgm == -1))
synaptics_report_slot(dev, 0, sgm);
else
synaptics_report_slot(dev, 0, NULL);
/*
* If the finger slot contained in AGM is valid, and either
* hasn't changed, or is new, then report AGM in MTB slot 1.
* Otherwise, empty MTB slot 1.
*/
if (mt_state->agm != -1 &&
(mt_state->agm == old->agm || old->agm == -1))
synaptics_report_slot(dev, 1, agm);
else
synaptics_report_slot(dev, 1, NULL);
break;
}
@ -633,29 +663,257 @@ static void synaptics_report_mt_data(struct psmouse *psmouse,
input_mt_report_pointer_emulation(dev, false);
/* Send the number of fingers reported by touchpad itself. */
input_mt_report_finger_count(dev, count);
input_mt_report_finger_count(dev, mt_state->count);
synaptics_report_buttons(psmouse, sgm);
input_sync(dev);
}
/* Handle case where mt_state->count = 0 */
static void synaptics_image_sensor_0f(struct synaptics_data *priv,
struct synaptics_mt_state *mt_state)
{
synaptics_mt_state_set(mt_state, 0, -1, -1);
priv->mt_state_lost = false;
}
/* Handle case where mt_state->count = 1 */
static void synaptics_image_sensor_1f(struct synaptics_data *priv,
struct synaptics_mt_state *mt_state)
{
struct synaptics_hw_state *agm = &priv->agm;
struct synaptics_mt_state *old = &priv->mt_state;
/*
* If the last AGM was (0,0,0), and there is only one finger left,
* then we absolutely know that SGM contains slot 0, and all other
* fingers have been removed.
*/
if (priv->agm_pending && agm->z == 0) {
synaptics_mt_state_set(mt_state, 1, 0, -1);
priv->mt_state_lost = false;
return;
}
switch (old->count) {
case 0:
synaptics_mt_state_set(mt_state, 1, 0, -1);
break;
case 1:
/*
* If mt_state_lost, then the previous transition was 3->1,
* and SGM now contains either slot 0 or 1, but we don't know
* which. So, we just assume that the SGM now contains slot 1.
*
* If pending AGM and either:
* (a) the previous SGM slot contains slot 0, or
* (b) there was no SGM slot
* then, the SGM now contains slot 1
*
* Case (a) happens with very rapid "drum roll" gestures, where
* slot 0 finger is lifted and a new slot 1 finger touches
* within one reporting interval.
*
* Case (b) happens if initially two or more fingers tap
* briefly, and all but one lift before the end of the first
* reporting interval.
*
* (In both these cases, slot 0 will becomes empty, so SGM
* contains slot 1 with the new finger)
*
* Else, if there was no previous SGM, it now contains slot 0.
*
* Otherwise, SGM still contains the same slot.
*/
if (priv->mt_state_lost ||
(priv->agm_pending && old->sgm <= 0))
synaptics_mt_state_set(mt_state, 1, 1, -1);
else if (old->sgm == -1)
synaptics_mt_state_set(mt_state, 1, 0, -1);
break;
case 2:
/*
* If mt_state_lost, we don't know which finger SGM contains.
*
* So, report 1 finger, but with both slots empty.
* We will use slot 1 on subsequent 1->1
*/
if (priv->mt_state_lost) {
synaptics_mt_state_set(mt_state, 1, -1, -1);
break;
}
/*
* Since the last AGM was NOT (0,0,0), it was the finger in
* slot 0 that has been removed.
* So, SGM now contains previous AGM's slot, and AGM is now
* empty.
*/
synaptics_mt_state_set(mt_state, 1, old->agm, -1);
break;
case 3:
/*
* Since last AGM was not (0,0,0), we don't know which finger
* is left.
*
* So, report 1 finger, but with both slots empty.
* We will use slot 1 on subsequent 1->1
*/
synaptics_mt_state_set(mt_state, 1, -1, -1);
priv->mt_state_lost = true;
break;
}
}
/* Handle case where mt_state->count = 2 */
static void synaptics_image_sensor_2f(struct synaptics_data *priv,
struct synaptics_mt_state *mt_state)
{
struct synaptics_mt_state *old = &priv->mt_state;
switch (old->count) {
case 0:
synaptics_mt_state_set(mt_state, 2, 0, 1);
break;
case 1:
/*
* If previous SGM contained slot 1 or higher, SGM now contains
* slot 0 (the newly touching finger) and AGM contains SGM's
* previous slot.
*
* Otherwise, SGM still contains slot 0 and AGM now contains
* slot 1.
*/
if (old->sgm >= 1)
synaptics_mt_state_set(mt_state, 2, 0, old->sgm);
else
synaptics_mt_state_set(mt_state, 2, 0, 1);
break;
case 2:
/*
* If mt_state_lost, SGM now contains either finger 1 or 2, but
* we don't know which.
* So, we just assume that the SGM contains slot 0 and AGM 1.
*/
if (priv->mt_state_lost)
synaptics_mt_state_set(mt_state, 2, 0, 1);
/*
* Otherwise, use the same mt_state, since it either hasn't
* changed, or was updated by a recently received AGM-CONTACT
* packet.
*/
break;
case 3:
/*
* 3->2 transitions have two unsolvable problems:
* 1) no indication is given which finger was removed
* 2) no way to tell if agm packet was for finger 3
* before 3->2, or finger 2 after 3->2.
*
* So, report 2 fingers, but empty all slots.
* We will guess slots [0,1] on subsequent 2->2.
*/
synaptics_mt_state_set(mt_state, 2, -1, -1);
priv->mt_state_lost = true;
break;
}
}
/* Handle case where mt_state->count = 3 */
static void synaptics_image_sensor_3f(struct synaptics_data *priv,
struct synaptics_mt_state *mt_state)
{
struct synaptics_mt_state *old = &priv->mt_state;
switch (old->count) {
case 0:
synaptics_mt_state_set(mt_state, 3, 0, 2);
break;
case 1:
/*
* If previous SGM contained slot 2 or higher, SGM now contains
* slot 0 (one of the newly touching fingers) and AGM contains
* SGM's previous slot.
*
* Otherwise, SGM now contains slot 0 and AGM contains slot 2.
*/
if (old->sgm >= 2)
synaptics_mt_state_set(mt_state, 3, 0, old->sgm);
else
synaptics_mt_state_set(mt_state, 3, 0, 2);
break;
case 2:
/*
* After some 3->1 and all 3->2 transitions, we lose track
* of which slot is reported by SGM and AGM.
*
* For 2->3 in this state, report 3 fingers, but empty all
* slots, and we will guess (0,2) on a subsequent 0->3.
*
* To userspace, the resulting transition will look like:
* 2:[0,1] -> 3:[-1,-1] -> 3:[0,2]
*/
if (priv->mt_state_lost) {
synaptics_mt_state_set(mt_state, 3, -1, -1);
break;
}
/*
* If the (SGM,AGM) really previously contained slots (0, 1),
* then we cannot know what slot was just reported by the AGM,
* because the 2->3 transition can occur either before or after
* the AGM packet. Thus, this most recent AGM could contain
* either the same old slot 1 or the new slot 2.
* Subsequent AGMs will be reporting slot 2.
*
* To userspace, the resulting transition will look like:
* 2:[0,1] -> 3:[0,-1] -> 3:[0,2]
*/
synaptics_mt_state_set(mt_state, 3, 0, -1);
break;
case 3:
/*
* If, for whatever reason, the previous agm was invalid,
* Assume SGM now contains slot 0, AGM now contains slot 2.
*/
if (old->agm <= 2)
synaptics_mt_state_set(mt_state, 3, 0, 2);
/*
* mt_state either hasn't changed, or was updated by a recently
* received AGM-CONTACT packet.
*/
break;
}
}
static void synaptics_image_sensor_process(struct psmouse *psmouse,
struct synaptics_hw_state *sgm)
{
int count;
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;
/*
* Update mt_state using the new finger count and current mt_state.
*/
if (sgm->z == 0)
count = 0;
synaptics_image_sensor_0f(priv, &mt_state);
else if (sgm->w >= 4)
count = 1;
synaptics_image_sensor_1f(priv, &mt_state);
else if (sgm->w == 0)
count = 2;
else
count = 3;
synaptics_image_sensor_2f(priv, &mt_state);
else if (sgm->w == 1)
synaptics_image_sensor_3f(priv, &mt_state);
/* Send resulting input events to user space */
synaptics_report_mt_data(psmouse, count, sgm);
synaptics_report_mt_data(psmouse, &mt_state, sgm);
/* Store updated mt_state */
priv->mt_state = agm->mt_state = mt_state;
priv->agm_pending = false;
}
/*

4
drivers/input/mouse/synaptics.h
View file

@ -161,11 +161,15 @@ struct synaptics_data {
struct serio *pt_port; /* Pass-through serio port */
struct synaptics_mt_state mt_state; /* Current mt finger state */
bool mt_state_lost; /* mt_state may be incorrect */
/*
* Last received Advanced Gesture Mode (AGM) packet. An AGM packet
* contains position data for a second contact, at half resolution.
*/
struct synaptics_hw_state agm;
bool agm_pending; /* new AGM packet received */
};
void synaptics_module_init(void);