linux-kernel - Re: [PATCH 2/2] hwmon: spd5118: Fail probe if SPD writes are disabled

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Message-ID: <6cd7920b-165d-43e4-9c60-aae9492bc814@roeck-us.net>
Date: Thu, 5 Feb 2026 05:46:18 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Tinsae Tadesse <tinsaetadesse2015@...il.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Jean Delvare <jdelvare@...e.com>,
	Andi Shyti <andi.shyti@...nel.org>, linux-i2c@...r.kernel.org,
	linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] hwmon: spd5118: Fail probe if SPD writes are disabled

On Thu, Feb 05, 2026 at 01:29:25PM +0300, Tinsae Tadesse wrote:
> SPD5118 requires write access for page selection, configuration,
> and cache synchronization during suspend/resume. If the host
> controller does not allow SPD writes, the driver cannot function
> properly.
> 
> Detect this state using adapter quirks and determine whether to
> stop the probe.
> 
> Signed-off-by: Tinsae Tadesse <tinsaetadesse2015@...il.com>
> ---
>  drivers/hwmon/spd5118.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
> index 5da44571b6a0..094d05472562 100644
> --- a/drivers/hwmon/spd5118.c
> +++ b/drivers/hwmon/spd5118.c
> @@ -525,6 +525,8 @@ static int spd5118_common_probe(struct device *dev, struct regmap *regmap,
>  	unsigned int capability, revision, vendor, bank;
>  	struct spd5118_data *data;
>  	struct device *hwmon_dev;
> +	struct i2c_client *client;
> +	const struct i2c_adapter_quirks *quirks;
>  	int err;
>  
>  	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> @@ -552,6 +554,19 @@ static int spd5118_common_probe(struct device *dev, struct regmap *regmap,
>  	if (!spd5118_vendor_valid(bank, vendor))
>  		return -ENODEV;
>  
> +	/*
> +	 * SPD5118 requires write access for correct operation
> +	 * (page selection, configuration, and suspend/resume cache sync).
> +	 * If the SPD writes are blocked by the SMBus controller, the
> +	 * probe fails.
> +	 */
> +	client = to_i2c_client(dev);
> +	quirks = client->adapter->quirks;
> +	if (quirks && (quirks->flags & I2C_AQ_SPD_WRITE_DISABLED)) {
> +		dev_err_probe(dev, -ENODEV, "SPD Write Disable is set on adapter; refusing probe\n");
> +		return -ENODEV;

		return dev_err_probe(...);

> +	}
> +
>  	data->regmap = regmap;
>  	mutex_init(&data->nvmem_lock);
>  	dev_set_drvdata(dev, data);
> -- 
> 2.52.0
>