linux-kernel - Re: [PATCH 1/2] hwmon: shtc1: add support for device tree bindings

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Date:   Thu, 2 Jul 2020 22:48:50 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Chris Ruehl <chris.ruehl@...ys.com.hk>
Cc:     Jack Lo <jack.lo@...ys.com.hk>, devicetree@...r.kernel.org,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] hwmon: shtc1: add support for device tree bindings

On 7/2/20 8:48 PM, Chris Ruehl wrote:
> Add support for DTS bindings to the shtc driver, use CONFIG_OF
> to compile in the code if needed.
> 

Ah, here it is. The introducing patch should say something like "[PATCH 0/2]".

> Signed-off-by: Chris Ruehl <chris.ruehl@...ys.com.hk>
> ---
>  drivers/hwmon/shtc1.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/hwmon/shtc1.c b/drivers/hwmon/shtc1.c
> index a0078ccede03..3bcabc1cbce8 100644
> --- a/drivers/hwmon/shtc1.c
> +++ b/drivers/hwmon/shtc1.c
> @@ -14,6 +14,9 @@
>  #include <linux/err.h>
>  #include <linux/delay.h>
>  #include <linux/platform_data/shtc1.h>
> +#ifdef CONFIG_OF

No. Please no conditional includes.

> +#include <linux/of.h>
> +#endif
>  
>  /* commands (high precision mode) */
>  static const unsigned char shtc1_cmd_measure_blocking_hpm[]    = { 0x7C, 0xA2 };
> @@ -196,6 +199,10 @@ static int shtc1_probe(struct i2c_client *client,
>  	enum shtcx_chips chip = id->driver_data;
>  	struct i2c_adapter *adap = client->adapter;
>  	struct device *dev = &client->dev;
> +#ifdef CONFIG_OF
> +	struct device_node *np = dev->of_node;
> +	u8 value;
> +#endif
>  
>  	if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
>  		dev_err(dev, "plain i2c transactions not supported\n");
> @@ -235,6 +242,20 @@ static int shtc1_probe(struct i2c_client *client,
>  
>  	if (client->dev.platform_data)
>  		data->setup = *(struct shtc1_platform_data *)dev->platform_data;
> +
> +#ifdef CONFIG_OF

Unnecessary ifdef. Selection of devicetree data or not can be made
based on np != NULL. Also, if devictree data is available, platform
data should be ignored to avoid confusion.

> +	if (np) {
> +		if (of_property_read_bool(np, "sensirion,blocking_io")) {
> +			of_property_read_u8(np, "sensirion,blocking_io", &value);
> +			data->setup.blocking_io = (value > 0) ? true : false;
> +		}
Why this complexity, and why not just make the property a boolean ?

> +		if (of_property_read_bool(np, "sensicon,high_precision")) {
> +			of_property_read_u8(np, "sensirion,high_precision", &value);
> +			data->setup.high_precision = (value > 0) ? true : false;

"sensicon,high_precision" should also be a boolean.

> +		}
> +	}
> +#endif
> +
>  	shtc1_select_command(data);
>  	mutex_init(&data->update_lock);
>  
> @@ -257,6 +278,15 @@ static const struct i2c_device_id shtc1_id[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, shtc1_id);
>  
> +#ifdef CONFIG_OF
> +static const struct of_device_id shtc1_of_match[] = {
> +	{ .compatible = "sensirion,shtc1" },
> +	{ .compatible = "sensirion,shtw1" },
> +	{ .compatible = "sensirion,shtc3" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, shtc1_of_match);
> +#endif
>  static struct i2c_driver shtc1_i2c_driver = {
>  	.driver.name  = "shtc1",
>  	.probe        = shtc1_probe,
> 
Not sure how this works without setting of_match_table. I guess it just works
accidentally because .id_table also provides a devicetree match. Still,
of_match_table should be set.

Guenter