linux-kernel - Re: [PATCH 1/3] hwmon: spd5118: Do not fail resume on temporary I2C errors

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Message-Id: <DG2EEU6SXFFE.20DWQUV1BW9QW@gmail.com>
Date: Fri, 30 Jan 2026 20:54:23 -0500
From: "Kurt Borja" <kuurtb@...il.com>
To: "Guenter Roeck" <linux@...ck-us.net>, "Kurt Borja" <kuurtb@...il.com>,
 "TINSAE TADESSE" <tinsaetadesse2015@...il.com>
Cc: "Armin Wolf" <W_Armin@....de>, "linux-hwmon@...r.kernel.org"
 <linux-hwmon@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Guenter
 Roeck" <groeck7@...il.com>
Subject: Re: [PATCH 1/3] hwmon: spd5118: Do not fail resume on temporary I2C
 errors

On Fri Jan 30, 2026 at 8:21 PM -05, Guenter Roeck wrote:
> Hi Kurt,
>
> On 1/30/26 16:55, Kurt Borja wrote:
>> On Tue Jan 27, 2026 at 6:41 PM -05, Guenter Roeck wrote:
>>> Hi,
>>>
>>> On Tue, Jan 27, 2026 at 10:23:24PM +0300, TINSAE TADESSE wrote:
>>>>
>>>> Disabling CONFIG_SENSORS_SPD5118_DETECT completely avoids the issue on
>>>> affected platforms,
>>>> even without any code changes. This confirms that the failures are
>>>> triggered specifically by automatic
>>>> SPD5118 instantiation on systems where the i801 controller enforces
>>>> SPD Write Disable.
>>>
>>> Thanks for confirming. Can you try if the patch below fixes the problem ?
>>> It is a wild shot, but it might be worth a try.
>>>
>>> Thanks,
>>> Guenter
>>>
>>> ---
>>>  From b44c31c2c779a67827e3144b818cf21f5efacea1 Mon Sep 17 00:00:00 2001
>>> From: Guenter Roeck <linux@...ck-us.net>
>>> Date: Tue, 27 Jan 2026 15:32:32 -0800
>>> Subject: [PATCH] hwmon: (spd5118) Explicitly enable temperature sensor in
>>>   probe function
>>>
>>> Instantiating the driver does not make sense if the temperature sensor
>>> is disabled, so enable it unconditionally in the probe function.
>>>
>>> If that fails, write operations to the chip are likely disabled
>>> by the I2C controller. Bail out with an eror message if that happens.
>>>
>>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>>> ---
>>>   drivers/hwmon/spd5118.c | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>>
>>> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
>>> index 5da44571b6a0..3e0e780014f9 100644
>>> --- a/drivers/hwmon/spd5118.c
>>> +++ b/drivers/hwmon/spd5118.c
>>> @@ -552,6 +552,11 @@ static int spd5118_common_probe(struct device *dev, struct regmap *regmap,
>>>   	if (!spd5118_vendor_valid(bank, vendor))
>>>   		return -ENODEV;
>>>   
>>> +	if (regmap_update_bits(regmap, SPD5118_REG_TEMP_CONFIG,
>>> +			       SPD5118_TS_DISABLE, 0) < 0)
>>> +		return dev_err_probe(dev, -ENODEV,
>>> +				     "Failed to enable temperature sensor\n");
>>> +
>>>   	data->regmap = regmap;
>>>   	mutex_init(&data->nvmem_lock);
>>>   	dev_set_drvdata(dev, data);
>> 
>> Hi Guenter,
>> 
>> I'm experiencing the same issue reported in this thread. This patch does
>> not fix it for me :(.
>> 
> Thanks for a note. Well, it was a wild shot, so it is not entirely surprising
> that it didn't work. I suspect regmap doesn't actually write the register
> if the value is unchanged. Another option might be to try writing a value

I tried forcing the write with

	bool change;
	err = regmap_update_bits_base(regmap, SPD5118_REG_TEMP_CONFIG,
				      SPD5118_TS_DISABLE, 0, &change, false, true);
	if (err)
		return dev_err_probe(dev, err,
				     "Failed to enable temperature sensor\n");

and it fails to probe

	spd5118 17-0051: error -ENXIO: Failed to enable temperature sensor
	spd5118 17-0053: error -ENXIO: Failed to enable temperature sensor


> (e.g., 0x01) into register 0x13 or 0x14. Those are "clear status" registers.
> If that fails, we would know that the chip is write protected.

I'll try this later too.

>
> Thanks,
> Guenter

-- 
Thanks,
 ~ Kurt