Re: [PATCH v3 2/2] Input: add Imagis touchscreen driver

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

On 15/02/2022 16:15, Markuss Broks wrote:
> Add support for the IST3038C touchscreen IC from Imagis, based on
> downstream driver. The driver supports multi-touch (10 touch points)
> The IST3038C IC supports touch keys, but the support isn't added
> because the touch screen used for testing doesn't utilize touch keys.
> Looking at the downstream driver, it is possible to add support
> for other Imagis ICs of IST30**C series.
> 
> Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
> ---
>  MAINTAINERS                        |   6 +
>  drivers/input/touchscreen/Kconfig  |  10 +
>  drivers/input/touchscreen/Makefile |   1 +
>  drivers/input/touchscreen/imagis.c | 330 +++++++++++++++++++++++++++++
>  4 files changed, 347 insertions(+)
>  create mode 100644 drivers/input/touchscreen/imagis.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a899828a8d4e..f7f717ae926a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9405,6 +9405,12 @@ F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml
>  F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
>  F:	drivers/iio/afe/iio-rescale.c
>  
> +IMAGIS TOUCHSCREEN DRIVER

Please read the line 143-144 of this file.

> +M:	Markuss Broks <markuss.broks@gmail.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
> +F:	drivers/input/touchscreen/imagis.c
> +
>  IKANOS/ADI EAGLE ADSL USB DRIVER
>  M:	Matthieu Castet <castet.matthieu@free.fr>
>  M:	Stanislaw Gruszka <stf_xl@wp.pl>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 2f6adfb7b938..6810b4b094e8 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1367,4 +1367,14 @@ config TOUCHSCREEN_ZINITIX
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called zinitix.
>  
> +config TOUCHSCREEN_IMAGIS

Here and in Makefile - do not add entries at the end, but
alphabetically. This reduces conflicts.

> +	tristate "Imagis touchscreen support"
> +	depends on I2C
> +	help
> +		Say Y here if you have an Imagis IST30xxC touchscreen.
> +		If unsure, say N.
> +
> +		To compile this driver as a module, choose M here: the
> +		module will be called imagis.
> +
>  endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 39a8127cf6a5..989bb1d563d3 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -115,3 +115,4 @@ obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
>  obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_IQS5XX)	+= iqs5xx.o
>  obj-$(CONFIG_TOUCHSCREEN_ZINITIX)	+= zinitix.o
> +obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o


(...)

> +
> +static int imagis_init_regulators(struct imagis_ts *ts)
> +{
> +	struct i2c_client *client = ts->client;
> +	int error;
> +
> +	ts->supplies[0].supply = "vdd";
> +	ts->supplies[1].supply = "vddio";
> +	error = devm_regulator_bulk_get(&client->dev,
> +					ARRAY_SIZE(ts->supplies),
> +					ts->supplies);
> +	if (error < 0) {
> +		dev_err(&client->dev, "Failed to get regulators: %d\n", error);

This should be also dev_err_probe() in case of deferred probing. On the
other hand, you already handle printing in probe(), so why doing it twice?

> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
> +static int imagis_probe(struct i2c_client *i2c)
> +{
> +	struct device *dev;
> +	struct imagis_ts *ts;
> +	int chip_id, ret;
> +
> +	dev = &i2c->dev;
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	ts->client = i2c;
> +
> +	ret = imagis_init_regulators(ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "regulator init error: %d\n", ret);
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(ts->supplies),
> +				    ts->supplies);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to enable regulators: %d\n", ret);
> +
> +	msleep(IST3038C_CHIP_ON_DELAY);
> +
> +	ret = imagis_i2c_read_reg(ts, IST3038C_REG_CHIPID | IST3038C_DIRECT_ACCESS, &chip_id);
> +	if (ret)

You miss here and other error paths the regulator cleanup (disabling).

> +		return dev_err_probe(dev, ret, "chip ID read failure: %d\n", ret);
> +
> +	if (chip_id == IST3038C_WHOAMI)
> +		dev_dbg(dev, "Detected IST3038C chip\n");
> +	else
> +		return dev_err_probe(dev, -EINVAL, "unknown chip ID: 0x%x\n", chip_id);
> +
> +	ret = devm_request_threaded_irq(dev, i2c->irq,
> +					NULL, imagis_interrupt,
> +					IRQF_ONESHOT | IRQF_TRIGGER_FALLING | IRQF_NO_AUTOEN,

The interrupt edge should come from DT, not be hard-coded. I think you
can safely skip IRQF_TRIGGER_FALLING.

> +					"imagis-touchscreen", ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "IRQ allocation failure: %d\n", ret);
> +
> +	ret = imagis_init_input_dev(ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "input subsystem init error: %d\n", ret);
> +
> +	return 0;
> +}
> +


Best regards,
Krzysztof