linux-kernel - Re: [PATCH v2] Input: pixcir_i2c_ts - add support for one-time total calibration

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Message-ID: <894b86b6-8b80-4ad1-942c-0e1120c0a4ae@ysoft.com>
Date: Thu, 18 Dec 2025 11:22:10 +0100
From: Michal Vokáč <michal.vokac@...ft.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
 Fabio Estevam <festevam@...il.com>
Subject: Re: [PATCH v2] Input: pixcir_i2c_ts - add support for one-time total
 calibration

Hi Dmitry,

gentle ping on this.

On 19. 11. 25 18:51, Michal Vokáč wrote:
> The Pixcir Tango controller has support for a one-time total calibration
> (manual calibration) procedure. Its purpose is to measure the capacitance
> offsets of the electrode system and to store these values into EEPROM.
> 
> During normal operation this calibration data is subtracted from the values
> measured. This calibration should be necessary only once in the product
> lifetime. It should be performed as part of the final adjustment after
> the panel is mounted in the product.
> 
> Add support for the calibration with sysfs interface.
> 
> Signed-off-by: Michal Vokáč <michal.vokac@...ft.com>
> ---
> changes in v2:
>   - Removed redundant lock from calibrate_store().
> 
>   drivers/input/touchscreen/pixcir_i2c_ts.c | 26 +++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/input/touchscreen/pixcir_i2c_ts.c b/drivers/input/touchscreen/pixcir_i2c_ts.c
> index dad5786e82a4..e52ec8d8e392 100644
> --- a/drivers/input/touchscreen/pixcir_i2c_ts.c
> +++ b/drivers/input/touchscreen/pixcir_i2c_ts.c
> @@ -24,6 +24,7 @@
>    */
>   #define PIXCIR_REG_POWER_MODE	51
>   #define PIXCIR_REG_INT_MODE	52
> +#define PIXCIR_REG_SPECOP	58
>   
>   /*
>    * Power modes:
> @@ -462,6 +463,30 @@ static int pixcir_i2c_ts_resume(struct device *dev)
>   static DEFINE_SIMPLE_DEV_PM_OPS(pixcir_dev_pm_ops,
>   				pixcir_i2c_ts_suspend, pixcir_i2c_ts_resume);
>   
> +static ssize_t calibrate_store(struct device *dev,
> +			       struct device_attribute *attr,
> +			       const char *buf, size_t count)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct pixcir_i2c_ts_data *ts = i2c_get_clientdata(client);
> +	static const u8 cmd = 0x03;
> +	int error;
> +
> +	error = i2c_smbus_write_byte_data(ts->client, PIXCIR_REG_SPECOP, cmd);
> +	if (error)
> +		dev_err(dev, "calibrate command failed: %d\n", error);
> +
> +	return error ?: count;
> +}
> +
> +static DEVICE_ATTR_WO(calibrate);
> +
> +static struct attribute *pixcir_i2c_ts_attrs[] = {
> +	&dev_attr_calibrate.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(pixcir_i2c_ts);
> +
>   static int pixcir_i2c_ts_probe(struct i2c_client *client)
>   {
>   	const struct i2c_device_id *id = i2c_client_get_device_id(client);
> @@ -600,6 +625,7 @@ MODULE_DEVICE_TABLE(of, pixcir_of_match);
>   static struct i2c_driver pixcir_i2c_ts_driver = {
>   	.driver = {
>   		.name	= "pixcir_ts",
> +		.dev_groups = pixcir_i2c_ts_groups,
>   		.pm	= pm_sleep_ptr(&pixcir_dev_pm_ops),
>   		.of_match_table = of_match_ptr(pixcir_of_match),
>   	},


Best regards,
Michal