Some maXTouch chips will not respond on the first I2C request when they are in
a sleep state. It must be retried after a delay for the chip to wake up.
Signed-off-by: Nick Dyer <nick.d...@itdev.co.uk>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 39 +++++++++++++++++++++---------
1 file changed, 27 insertions(+), 12 deletions(-)
diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c
b/drivers/input/touchscreen/atmel_mxt_ts.c
index 6ab7ef6..b0dcae4 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -193,6 +193,7 @@ struct t9_range {
#define MXT_RESET_TIME 200 /* msec */
#define MXT_RESET_NOCHGREAD 400 /* msec */
#define MXT_FWRESET_TIME 1000 /* msec */
+#define MXT_WAKEUP_TIME 25 /* msec */
/* Command to unlock bootloader */
#define MXT_UNLOCK_CMD_MSB 0xaa
@@ -503,6 +504,7 @@ static int __mxt_read_reg(struct i2c_client *client,
struct i2c_msg xfer[2];
u8 buf[2];
int ret;
+ bool retry = false;
buf[0] = reg & 0xff;
buf[1] = (reg >> 8) & 0xff;
@@ -519,17 +521,22 @@ static int __mxt_read_reg(struct i2c_client *client,
xfer[1].len = len;
xfer[1].buf = val;
- ret = i2c_transfer(client->adapter, xfer, 2);
- if (ret == 2) {
- ret = 0;
- } else {
- if (ret >= 0)
- ret = -EIO;
- dev_err(&client->dev, "%s: i2c transfer failed (%d)\n",
- __func__, ret);
+retry_read:
+ ret = i2c_transfer(client->adapter, xfer, ARRAY_SIZE(xfer));
+ if (ret != ARRAY_SIZE(xfer)) {
+ if (!retry) {
+ dev_dbg(&client->dev, "%s: i2c retry\n", __func__);
+ msleep(MXT_WAKEUP_TIME);
+ retry = true;
+ goto retry_read;
+ } else {
+ dev_err(&client->dev, "%s: i2c transfer failed (%d)\n",
+ __func__, ret);
+ return -EIO;
+ }
}
- return ret;
+ return 0;
}
static int __mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
@@ -538,6 +545,7 @@ static int __mxt_write_reg(struct i2c_client *client, u16
reg, u16 len,
u8 *buf;
size_t count;
int ret;
+ bool retry = false;
count = len + 2;
buf = kmalloc(count, GFP_KERNEL);
@@ -548,14 +556,21 @@ static int __mxt_write_reg(struct i2c_client *client, u16
reg, u16 len,
buf[1] = (reg >> 8) & 0xff;
memcpy(&buf[2], val, len);
+retry_write:
ret = i2c_master_send(client, buf, count);
if (ret == count) {
ret = 0;
} else {
- if (ret >= 0)
+ if (!retry) {
+ dev_dbg(&client->dev, "%s: i2c retry\n", __func__);
+ msleep(MXT_WAKEUP_TIME);
+ retry = true;
+ goto retry_write;
+ } else {
+ dev_err(&client->dev, "%s: i2c send failed (%d)\n",
+ __func__, ret);
ret = -EIO;
- dev_err(&client->dev, "%s: i2c send failed (%d)\n",
- __func__, ret);
+ }
}
kfree(buf);
--
1.7.10.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
