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Input: edt-ft5x06 - work around first register access error

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The EP0700MLP1 returns bogus data on the first register read access
(reading the threshold parameter from register 0x00):

    edt_ft5x06 2-0038: crc error: 0xfc expected, got 0x40

It ignores writes until then. This patch adds a dummy read after which
the number of sensors and parameter read/writes work correctly.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Philipp Zabel 2020-01-09 17:03:21 -08:00 committed by Dmitry Torokhov
parent fd7bba685e
commit e112324cc0
1 changed files with 7 additions and 0 deletions
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7
drivers/input/touchscreen/edt-ft5x06.c
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@ -1050,6 +1050,7 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client,
{
const struct edt_i2c_chip_data *chip_data;
struct edt_ft5x06_ts_data *tsdata;
u8 buf[2] = { 0xfc, 0x00 };
struct input_dev *input;
unsigned long irq_flags;
int error;
@ -1140,6 +1141,12 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client,
return error;
}
/*
* Dummy read access. EP0700MLP1 returns bogus data on the first
* register read access and ignores writes.
*/
edt_ft5x06_ts_readwrite(tsdata->client, 2, buf, 2, buf);
edt_ft5x06_ts_set_regs(tsdata);
edt_ft5x06_ts_get_defaults(&client->dev, tsdata);
edt_ft5x06_ts_get_parameters(tsdata);