Re: [PATCH v3 1/6] Input: edt-ft5x06: work around first register access error

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, Jan 08, 2020 at 12:10:45PM +0100, Marco Felsch wrote:
> From: Philipp Zabel <p.zabel@pengutronix.de>
> 
> 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>

Applied, thank you.

> ---
>  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 d61731c0037d..b87b1e074f62 100644
> --- a/drivers/input/touchscreen/edt-ft5x06.c
> +++ b/drivers/input/touchscreen/edt-ft5x06.c
> @@ -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);
> -- 
> 2.20.1
> 

-- 
Dmitry