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Date: Thu, 30 May 2024 11:08:12 +0200
From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-hwmon@vger.kernel.org, Hristo Venev <hristo@venev.name>, 
	=?utf-8?B?UmVuw6k=?= Rebe <rene@exactcode.de>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley <conor+dt@kernel.org>, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org, Radu Sabau <radu.sabau@analog.com>
Subject: Re: [PATCH 2/3] hwmon: Add support for SPD5118 compliant temperature
 sensors
Message-ID: <45396bd5-adb8-485a-98d0-eecfb7439bfa@t-8ch.de>
References: <20240529205204.81208-1-linux@roeck-us.net>
 <20240529205204.81208-3-linux@roeck-us.net>
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In-Reply-To: <20240529205204.81208-3-linux@roeck-us.net>

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@exactcode.de>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---

<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>