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maXTouch: Fix error in state machine

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This commit is contained in:
Gregory Nutt 2014-07-12 11:23:07 -06:00
parent 8d1feb7a54
commit 4548ea731e
1 changed files with 42 additions and 17 deletions
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59
drivers/input/mxt.c
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@ -86,14 +86,31 @@
/**************************************************************************** /****************************************************************************
* Private Types * Private Types
****************************************************************************/ ****************************************************************************/
/* This describes the state of one contact */ /* This enumeration describes the state of one contact.
*
* |
* v
* CONTACT_NONE (1) Touch
* / (1) ^ (3) (2) Release
* v \ (3) Event reported
* CONTACT_NEW CONTACT_LOST
* \ (3) ^ (2)
* v /
* CONTACT_REPORT
* \ (1) ^ (3)
* v /
* CONTACT_MOVE
*
* NOTE: This state transition diagram is simplified. There are a few other
* sneaky transitions to handle unexpected conditions.
*/
enum mxt_contact_e enum mxt_contact_e
{ {
CONTACT_NONE = 0, /* No contact */ CONTACT_NONE = 0, /* No contact */
CONTACT_NEW, /* New contact */ CONTACT_NEW, /* New contact */
CONTACT_MOVE, /* Same contact, possibly different position */ CONTACT_MOVE, /* Same contact, possibly different position */
CONTACT_REPORT, /* Contact reported*/ CONTACT_REPORT, /* Contact reported */
CONTACT_LOST, /* Contact lost */ CONTACT_LOST, /* Contact lost */
}; };
@ -790,6 +807,22 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
return; return;
} }
/* State is one of CONTACT_NEW, CONTACT_MOVE, CONTACT_REPORT or
* CONTACT_LOST.
*
* NOTE: Here we do not check for these other states because there is
* not much that can be done anyway. The transition to CONTACK_LOST
* really only makes sense if the preceding state was CONTACT_REPORT.
* If we were in (unreported) CONTACT_NEW or CONTACT_MOVE states, then
* this will overwrite that event and it will not be reported. This
* opens the possibility for contact lost reports when no contact was
* ever reported.
*
* We could improve this be leaving the unreported states in place,
* remembering that the contact was lost, and then reporting the loss-
* of-contact after touch state is reported.
*/
sample->contact = CONTACT_LOST; sample->contact = CONTACT_LOST;
} }
else else
@ -813,17 +846,7 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
sample->pressure = pressure; sample->pressure = pressure;
sample->valid = true; sample->valid = true;
/* If the last loss-of-contact event has not been processed yet, then /* If this is not the first touch report, then report it as a move:
* let's bump up the touch identifier and hope that the client is smart
* enough to infer the loss-of-contact event for the preceding touch.
*/
if (sample->contact == CONTACT_LOST)
{
priv->id++;
}
/* If this is not the first touch report, then report it a move:
* Same contact, same ID, but a potentially new position. If * Same contact, same ID, but a potentially new position. If
* The move event has not been reported, then just overwrite the * The move event has not been reported, then just overwrite the
* move. That is harmless. * move. That is harmless.
@ -846,7 +869,7 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
* data. * data.
* *
* This the state must be one of CONTACT_NONE or CONTACT_LOST (see * This the state must be one of CONTACT_NONE or CONTACT_LOST (see
* above) and we have a new contact with a new ID> * above) and we have a new contact with a new ID.
*/ */
else if (sample->contact != CONTACT_NEW) else if (sample->contact != CONTACT_NEW)
@ -1344,16 +1367,18 @@ static ssize_t mxt_read(FAR struct file *filep, FAR char *buffer, size_t len)
} }
else else
{ {
if (sample->contact == CONTACT_REPORT) /* We have contact. Is it the first contact? */
if (sample->contact == CONTACT_NEW)
{ {
/* First loss of contact */ /* Yes.. first contact. */
point->flags = TOUCH_DOWN | TOUCH_ID_VALID | point->flags = TOUCH_DOWN | TOUCH_ID_VALID |
TOUCH_POS_VALID; TOUCH_POS_VALID;
} }
else /* if (sample->contact == CONTACT_MOVE) */ else /* if (sample->contact == CONTACT_MOVE) */
{ {
/* Movement of the same contact */ /* No.. then it must be movement of the same contact */
point->flags = TOUCH_MOVE | TOUCH_ID_VALID | point->flags = TOUCH_MOVE | TOUCH_ID_VALID |
TOUCH_POS_VALID; TOUCH_POS_VALID;