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Subject[PATCH v1 28/63] Input: atmel_mxt_ts - implement I2C retries
Date
From: Nick Dyer <nick.dyer@itdev.co.uk>

Some maXTouch chips (eg mXT1386) 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.dyer@itdev.co.uk>
Acked-by: Yufeng Shen <miletus@chromium.org>
(cherry picked from ndyer/linux/for-upstream commit 63fd7a2cd03c3a572a5db39c52f4856819e1835d)
[gdavis: Forward port and fix conflicts.]
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
drivers/input/touchscreen/atmel_mxt_ts.c | 45 ++++++++++++++++--------
1 file changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index d3e1cd677aa7..86c016dbec0d 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -216,6 +216,7 @@ enum t100_type {
#define MXT_CRC_TIMEOUT 1000 /* msec */
#define MXT_FW_RESET_TIME 3000 /* msec */
#define MXT_FW_CHG_TIMEOUT 300 /* msec */
+#define MXT_WAKEUP_TIME 25 /* msec */
#define MXT_REGULATOR_DELAY 150 /* msec */
#define MXT_CHG_DELAY 100 /* msec */
#define MXT_POWERON_DELAY 150 /* msec */
@@ -723,6 +724,7 @@ 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;
@@ -739,17 +741,22 @@ 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_read_blks(struct mxt_data *data, u16 start, u16 count, u8 *buf)
@@ -779,6 +786,7 @@ 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);
@@ -789,14 +797,21 @@ 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 (ret != count) {
+ 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);
+ }
+ } else {
+ ret = 0;
}

kfree(buf);
--
2.19.2
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