21.08.2020 11:22, Jiada Wang пишет:
> From: Nick Dyer <nick.dyer@xxxxxxxxxxx>
>
> 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@xxxxxxxxxxx>
> Acked-by: Yufeng Shen <miletus@xxxxxxxxxxxx>
> (cherry picked from ndyer/linux/for-upstream commit 63fd7a2cd03c3a572a5db39c52f4856819e1835d)
> [gdavis: Forward port and fix conflicts.]
> Signed-off-by: George G. Davis <george_davis@xxxxxxxxxx>
> Signed-off-by: Jiada Wang <jiada_wang@xxxxxxxxxx>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 45 ++++++++++++++++--------
> 1 file changed, 30 insertions(+), 15 deletions(-)
Hello, Jiada!
I tested this patch on Acer A500 that has mXT1386 controller which
requires the I2C retrying and everything working good, no problems
spotted! Touchscreen doesn't work without this patch!
Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx>
I have one minor comment, please see it below!
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index a2189739e30f..e93eda1f3d59 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -196,6 +196,7 @@ 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 */
>
> /* Command to unlock bootloader */
> #define MXT_UNLOCK_CMD_MSB 0xaa
> @@ -626,6 +627,7 @@ 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;
> @@ -642,17 +644,22 @@ 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)) {
Is it really possible to get a positive ret != 2 from i2c_transfer()?
Maybe it's better to keep the old code behaviour by returning the "ret"
value directly if it's not equal to ARRAY_SIZE(xfer)?
