From: Philipp Zabel <p.zabel@pengutronix.de> [ Upstream commit e112324cc0422c046f1cf54c56f333d34fa20885 ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/input/touchscreen/edt-ft5x06.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c index 1e18ca0..3fdaa64 100644 --- a/drivers/input/touchscreen/edt-ft5x06.c +++ b/drivers/input/touchscreen/edt-ft5x06.c @@ -968,6 +968,7 @@ 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; @@ -1037,6 +1038,12 @@ 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); -- 1.8.3