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

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Message-ID: <6da5b1c1-bbe5-40a8-8363-3213265fe848@roeck-us.net>
Date: Mon, 12 Jan 2026 08:36:45 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Armin Wolf <W_Armin@....de>, Tinsae Tadesse <tinsaetadesse2015@...il.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] hwmon: spd5118: Do not fail resume on temporary I2C
 errors

On 1/10/26 14:27, Armin Wolf wrote:
> Am 10.01.26 um 18:19 schrieb Tinsae Tadesse:
> 
>> SPD5118 DDR5 temperature sensors may be temporarily unavailable
>> during s2idle resume. Ignore temporary -ENXIO and -EIO errors during resume and allow
>> register synchronization to be retried later.
> 
> Hi,
> 
> do you know if the error is caused by the SPD5118 device itself or by the underlying
> i2c controller? Please also share the output of "acpidump" and the name of the i2c
> controller used to communicate with the SPD5118.
> 
>> Signed-off-by: Tinsae Tadesse <tinsaetadesse2015@...il.com>
>> ---
>>   drivers/hwmon/spd5118.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
>> index 5da44571b6a0..ec9f14f6e0df 100644
>> --- a/drivers/hwmon/spd5118.c
>> +++ b/drivers/hwmon/spd5118.c
>> @@ -512,9 +512,15 @@ static int spd5118_resume(struct device *dev)
>>   {
>>       struct spd5118_data *data = dev_get_drvdata(dev);
>>       struct regmap *regmap = data->regmap;
>> +    int ret;
>>       regcache_cache_only(regmap, false);
>> -    return regcache_sync(regmap);
>> +    ret = regcache_sync(regmap);
>> +    if(ret == -ENXIO || ret == -EIO) {
>> +        dev_warn(dev, "SPD hub not responding on resume (%d), deferring init\n", ret);
>> +        return 0;
>> +    }
> 
> The specification says that the SPD5118 might take up to 10ms to initialize its i2c interface
> after power on. Can you test if simply waiting for 10ms before syncing the regcache solves this
> issue?
> 

It seems to be highly unlikely that this code executes within 10ms of powering on the memory.

Guenter

> Thanks,
> Armin Wolf
> 
>> +    return ret;
>>   }
>>   static DEFINE_SIMPLE_DEV_PM_OPS(spd5118_pm_ops, spd5118_suspend, spd5118_resume);
>