linux-kernel - Re: [PATCH 3/4] hwmon: Add support for Amphenol ChipCap 2

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Date:   Thu, 9 Nov 2023 09:59:04 +0100
From:   Javier Carrasco <javier.carrasco.cruz@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH 3/4] hwmon: Add support for Amphenol ChipCap 2



On 09.11.23 09:40, Krzysztof Kozlowski wrote:
> On 08/11/2023 17:35, Javier Carrasco wrote:
>>>> +
>>>> +	data->regulator = devm_regulator_get_optional(dev, "vdd");
>>>> +	if (!IS_ERR(data->regulator)) {
>>>> +		ret = cc2_retrive_alarm_config(data);
>>>> +		if (ret)
>>>> +			goto cleanup;
>>>> +	} else {
>>>> +		/* No access to EEPROM without regulator: no alarm control */
>>>
>>> Test your code with deferred probe. Are you sure you handle it
>>> correctly? To me, it looks like you handle deferred probe the same as
>>> any error.
>>>
>> The -EPROBE_DEFER is propagated to the probe function and it is the
>> returned value. I clarified the error path in v2 so no error messages
> 
> Really?
> 
> I see:
> if (!IS_ERR(data->regulator)) {
> 	// so you do not go here
> } else {
> 	goto dev_register;
> }
> dev_register is not error path. So how do you return EPROBE_DEFER?
> 
> Which line of code does it?
> 
EPROBE_DEFER is returned if the command window was missed, which is
checked in cc2_retrieve_alarm_config() (there is a typo I just corrected
-> cc2_retrive_alarm_config() in the current version). It could then
happen where you added a comment, but not because
devm_regulator_get_optional() failed.

Are you expecting a probe deferring if devm_regulator_get_optional()
fails as well? Like if the regulator is still not ready when the
function is called.
>> are displayed in that case, going directly to the dev_err_probe in the
>> probe cleanup.
>> When the EPROBE_DEFER error is returned, the probe function is deferred
>> and called again later on, which is the desired behavior.
>>
> 
> 
> Best regards,
> Krzysztof
> 
Best regards,
Javier Carrasco