mako: touch: preserving touch data coherency
Synaptics firmware maintains internal cache to store a scan of
finger data so that the host reads finger data from this cache.
The firmware updates the cache when the host reads it nonsequentially.
The current driver reads only present finger data, which can cause
unexpected nonsequential access to cache and the cache can be updated
before the host reads the data, resulting in losing finger data coherency.
Modified the driver to access data sequentially even if there are
not present fingers in the middle so that the finger data coherency
can be preserved.
Change-Id: I4b975c2ab2445078f2a81c3dd4ce484002d27933
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/drivers/input/touchscreen/touch_synaptics.c b/drivers/input/touchscreen/touch_synaptics.c
index e7a2a22..53961f4 100644
--- a/drivers/input/touchscreen/touch_synaptics.c
+++ b/drivers/input/touchscreen/touch_synaptics.c
@@ -156,6 +156,17 @@
#define CHARGER_CONNECTED 0x20
+static inline int get_highest_id(u32 fs)
+{
+ int id = 10;
+ int tmp = 0x000C0000;
+ while(!(fs & tmp)) {
+ id--;
+ tmp >>= 2;
+ }
+ return id;
+}
+
int synaptics_ts_get_data(struct i2c_client *client, struct t_data* data,
struct b_data* button, u8* total_num)
{
@@ -234,13 +245,20 @@
TOUCH_INFO_MSG("Touch_bit_mask: 0x%x\n", finger_status);
}
+ if (finger_status) {
+ int max_id = get_highest_id(finger_status);
+ if (unlikely(touch_i2c_read(ts->client,
+ FINGER_DATA_REG_START,
+ NUM_OF_EACH_FINGER_DATA_REG * max_id,
+ ts->ts_data.finger.finger_reg[0]) < 0)) {
+ TOUCH_ERR_MSG("FINGER_STATE_REG read fail\n");
+ goto err_synaptics_getdata;
+ }
+ }
+
for (id = 0; id < ts->pdata->caps->max_id; id++) {
switch (((finger_status >> (id*2)) & 0x3)) {
case FINGER_STATE_PRESENT_VALID:
- touch_i2c_read(ts->client,
- FINGER_DATA_REG_START + NUM_OF_EACH_FINGER_DATA_REG * id,
- NUM_OF_EACH_FINGER_DATA_REG,
- ts->ts_data.finger.finger_reg[id]);
data[id].state = ABS_PRESS;
data[id].x_position = TS_SNTS_GET_X_POSITION(
ts->ts_data.finger.finger_reg[id][REG_X_POSITION],