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Date: Sat, 1 Jun 2024 19:07:26 +0200
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Subject: Re: [PATCH v4 3/3] Input: novatek-nvt-ts: add support for NT36672A
 touchscreen
To: joelselvaraj.oss@gmail.com, Dmitry Torokhov <dmitry.torokhov@gmail.com>,
 Rob Herring <robh@kernel.org>, Krzysztof Kozlowski <krzk+dt@kernel.org>,
 Conor Dooley <conor+dt@kernel.org>,
 =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Cc: linux-input@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org
References: <20240601-nvt-ts-devicetree-regulator-support-v4-0-e0c0174464c4@gmail.com>
 <20240601-nvt-ts-devicetree-regulator-support-v4-3-e0c0174464c4@gmail.com>
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From: Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20240601-nvt-ts-devicetree-regulator-support-v4-3-e0c0174464c4@gmail.com>
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Hi Joel,

Thank you for the new version.

On 6/1/24 5:30 PM, Joel Selvaraj via B4 Relay wrote:
> From: Joel Selvaraj <joelselvaraj.oss@gmail.com>
> 
> Extend the novatek touchscreen driver to support NT36672A chip which
> is found in phones like qcom/sdm845-xiaomi-beryllium-tianma.dts.
> Added devicetree support for the driver and used i2c chip data to handle
> the variation in chip id and wake type. Also added vcc and iovcc
> regulators which are used to power the touchscreen hardware.
> 
> Signed-off-by: Joel Selvaraj <joelselvaraj.oss@gmail.com>
> ---
>  drivers/input/touchscreen/novatek-nvt-ts.c | 70 +++++++++++++++++++++++++++---
>  1 file changed, 64 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/novatek-nvt-ts.c b/drivers/input/touchscreen/novatek-nvt-ts.c
> index 9bee3a0c122fb..c24c33f609eb8 100644
> --- a/drivers/input/touchscreen/novatek-nvt-ts.c
> +++ b/drivers/input/touchscreen/novatek-nvt-ts.c
> @@ -31,9 +31,6 @@
>  #define NVT_TS_PARAMS_CHIP_ID		0x0e
>  #define NVT_TS_PARAMS_SIZE		0x0f
>  
> -#define NVT_TS_SUPPORTED_WAKE_TYPE	0x05
> -#define NVT_TS_SUPPORTED_CHIP_ID	0x05
> -
>  #define NVT_TS_MAX_TOUCHES		10
>  #define NVT_TS_MAX_SIZE			4096
>  
> @@ -51,11 +48,18 @@ static const int nvt_ts_irq_type[4] = {
>  	IRQF_TRIGGER_HIGH
>  };
>  
> +struct nvt_ts_i2c_chip_data {
> +	u8 wake_type;
> +	u8 chip_id;
> +};
> +
>  struct nvt_ts_data {
>  	struct i2c_client *client;
>  	struct input_dev *input;
>  	struct gpio_desc *reset_gpio;
> +	struct regulator_bulk_data regulators[2];
>  	struct touchscreen_properties prop;
> +	const struct nvt_ts_i2c_chip_data *chip;

Almost there. I have one remark which requires fixing below,
so since a v5 will be necessary anyways I also spotted another
small possible improvement:

Since you only use chip->wake_type and chip->chip_id
inside probe() you can make this chip pointer a local
variable in probe(). This saves having this stored
on the kernel heap even though it is never used again.

>  	int max_touches;
>  	u8 buf[NVT_TS_TOUCH_SIZE * NVT_TS_MAX_TOUCHES];
>  };
> @@ -142,6 +146,13 @@ static irqreturn_t nvt_ts_irq(int irq, void *dev_id)
>  static int nvt_ts_start(struct input_dev *dev)
>  {
>  	struct nvt_ts_data *data = input_get_drvdata(dev);
> +	int error;
> +
> +	error = regulator_bulk_enable(ARRAY_SIZE(data->regulators), data->regulators);
> +	if (error) {
> +		dev_err(&data->client->dev, "failed to enable regulators\n");
> +		return error;
> +	}
>  
>  	enable_irq(data->client->irq);
>  	gpiod_set_value_cansleep(data->reset_gpio, 0);
> @@ -155,6 +166,7 @@ static void nvt_ts_stop(struct input_dev *dev)
>  
>  	disable_irq(data->client->irq);
>  	gpiod_set_value_cansleep(data->reset_gpio, 1);
> +	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
>  }
>  
>  static int nvt_ts_suspend(struct device *dev)
> @@ -199,9 +211,31 @@ static int nvt_ts_probe(struct i2c_client *client)
>  	if (!data)
>  		return -ENOMEM;
>  
> +	data->chip = device_get_match_data(&client->dev);
> +	if (!data->chip)
> +		return -EINVAL;
> +

As mentioned above instead of data->chip you can use a local
"chip" variable here.

>  	data->client = client;
>  	i2c_set_clientdata(client, data);
>  
> +	/*
> +	 * VCC is the analog voltage supply
> +	 * IOVCC is the digital voltage supply
> +	 */
> +	data->regulators[0].supply = "vcc";
> +	data->regulators[1].supply = "iovcc";
> +	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->regulators), data->regulators);
> +	if (error) {
> +		dev_err(dev, "cannot get regulators: %d\n", error);
> +		return error;
> +	}
> +
> +	error = regulator_bulk_enable(ARRAY_SIZE(data->regulators), data->regulators);
> +	if (error) {
> +		dev_err(dev, "failed to enable regulators: %d\n", error);
> +		return error;
> +	}
> +
>  	data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>  	error = PTR_ERR_OR_ZERO(data->reset_gpio);
>  	if (error) {

Almost there. You need to disable the regulators when probe fails to
avoid an error from the regulator core about unbalanced enable/disable
of the regulators when the devm framework releases them.

So you need to add a regulator_bulk_disable() call in
the "if (error) {" branch here:

  	data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
  	error = PTR_ERR_OR_ZERO(data->reset_gpio);
  	if (error) {
		regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
		dev_err(dev, "failed to request reset GPIO: %d\n", error);
		return error;
	}

And ... (continued below)

> @@ -216,6 +250,11 @@ static int nvt_ts_probe(struct i2c_client *client)
>  	gpiod_set_value_cansleep(data->reset_gpio, 1); /* Put back in reset */
>  	if (error)
>  		return error;
> +	error = regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);

I would not error check this, just like how it is not error checked
in void nvt_ts_stop() and then I would move it to above the error
checking for the nvt_ts_read_data(...NVT_TS_PARAMETERS...), to avoid
the need for an extra regulator_bulk_disable() call in the if (error)
path for the nvt_ts_read_data() call.

So make the code look like this:

        error = nvt_ts_read_data(data->client, NVT_TS_PARAMETERS_START,
                                 data->buf, NVT_TS_PARAMS_SIZE);
        gpiod_set_value_cansleep(data->reset_gpio, 1); /* Put back in reset */
	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
        if (error)
                return error;

        width  = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_WIDTH]);
        height = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_HEIGHT]);
	...

This way you only need one extra regulator_bulk_disable() call for
error-exit paths in the case of devm_gpiod_get(dev, "reset", ...)
failing.

Regards,

Hans


> @@ -225,8 +264,8 @@ static int nvt_ts_probe(struct i2c_client *client)
>  	if (width > NVT_TS_MAX_SIZE || height >= NVT_TS_MAX_SIZE ||
>  	    data->max_touches > NVT_TS_MAX_TOUCHES ||
>  	    irq_type >= ARRAY_SIZE(nvt_ts_irq_type) ||
> -	    data->buf[NVT_TS_PARAMS_WAKE_TYPE] != NVT_TS_SUPPORTED_WAKE_TYPE ||
> -	    data->buf[NVT_TS_PARAMS_CHIP_ID] != NVT_TS_SUPPORTED_CHIP_ID) {
> +	    data->buf[NVT_TS_PARAMS_WAKE_TYPE] != data->chip->wake_type ||
> +	    data->buf[NVT_TS_PARAMS_CHIP_ID] != data->chip->chip_id) {
>  		dev_err(dev, "Unsupported touchscreen parameters: %*ph\n",
>  			NVT_TS_PARAMS_SIZE, data->buf);
>  		return -EIO;
> @@ -277,8 +316,26 @@ static int nvt_ts_probe(struct i2c_client *client)
>  	return 0;
>  }
>  
> +static const struct nvt_ts_i2c_chip_data nvt_nt11205_ts_data = {
> +	.wake_type = 0x05,
> +	.chip_id = 0x05,
> +};
> +
> +static const struct nvt_ts_i2c_chip_data nvt_nt36672a_ts_data = {
> +	.wake_type = 0x01,
> +	.chip_id = 0x08,
> +};
> +
> +static const struct of_device_id nvt_ts_of_match[] = {
> +	{ .compatible = "novatek,nt11205-ts", .data = &nvt_nt11205_ts_data },
> +	{ .compatible = "novatek,nt36672a-ts", .data = &nvt_nt36672a_ts_data },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, nvt_ts_of_match);
> +
>  static const struct i2c_device_id nvt_ts_i2c_id[] = {
> -	{ "nt11205-ts" },
> +	{ "nt11205-ts", (unsigned long) &nvt_nt11205_ts_data },
> +	{ "nt36672a-ts", (unsigned long) &nvt_nt36672a_ts_data },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(i2c, nvt_ts_i2c_id);
> @@ -287,6 +344,7 @@ static struct i2c_driver nvt_ts_driver = {
>  	.driver = {
>  		.name	= "novatek-nvt-ts",
>  		.pm	= pm_sleep_ptr(&nvt_ts_pm_ops),
> +		.of_match_table = nvt_ts_of_match,
>  	},
>  	.probe = nvt_ts_probe,
>  	.id_table = nvt_ts_i2c_id,
>