Re: [PATCH 2/3] hwmon: Add support for SPD5118 compliant temperature sensors

[Thomas Weißschuh]

On 2024-05-29 13:52:03+0000, Guenter Roeck wrote:
> Add support for SPD5118 (Jedec JESD300-5B.01) compliant temperature
> sensors. Such sensors are typically found on DDR5 memory modules.
> 
> Cc: René Rebe <rene@xxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---

<snip>

> +/* Return 0 if detection is successful, -ENODEV otherwise */
> +static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
> +{
> +	struct i2c_adapter *adapter = client->adapter;
> +	int regval;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> +				     I2C_FUNC_SMBUS_WORD_DATA))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
> +	if (regval != 0x5118)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
> +	if (regval < 0 || !spd5118_vendor_valid(regval & 0xff, regval >> 8))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
> +	if (regval < 0)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
> +	if (regval)
> +		return -ENODEV;
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
> +	if (regval)
> +		return -ENODEV;
> +
> +	if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
> +		return -ENODEV;

This breaks automatic detection for me.

I think the test should after the read of SPD5118_REG_CAPABILITY and
test that register, similar on how it is done in _probe().

> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
> +	if (regval < 0 || (regval & 0xc1))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
> +	if (regval < 0)
> +		return -ENODEV;
> +	if (regval & ~SPD5118_TS_DISABLE)
> +		return -ENODEV;
> +
> +	strscpy(info->type, "spd5118", I2C_NAME_SIZE);
> +	return 0;
> +}

<snip>