linux-kernel - Re: [PATCH V6 5/5] thermal: qcom: add support for PMIC5 Gen3 ADC thermal monitoring

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Message-ID: <b453e9c1-c87d-457b-8ee8-4b82a6417385@oss.qualcomm.com>
Date: Tue, 24 Jun 2025 18:58:47 +0530
From: Jishnu Prakash <jishnu.prakash@....qualcomm.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: robh@...nel.org, krzysztof.kozlowski@...aro.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, agross@...nel.org, andersson@...nel.org,
        lumag@...nel.org, dmitry.baryshkov@....qualcomm.com,
        konradybcio@...nel.org, daniel.lezcano@...aro.org, sboyd@...nel.org,
        amitk@...nel.org, thara.gopinath@...il.com, lee@...nel.org,
        rafael@...nel.org, subbaraman.narayanamurthy@....qualcomm.com,
        david.collins@....qualcomm.com, anjelique.melendez@....qualcomm.com,
        quic_kamalw@...cinc.com, rui.zhang@...el.com, lukasz.luba@....com,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, cros-qcom-dts-watchers@...omium.org,
        quic_skakitap@...cinc.com, neil.armstrong@...aro.org,
        stephan.gerhold@...aro.org
Subject: Re: [PATCH V6 5/5] thermal: qcom: add support for PMIC5 Gen3 ADC
 thermal monitoring

Hi Jonathan,

On 5/11/2025 6:41 PM, Jonathan Cameron wrote:
> On Fri,  9 May 2025 16:39:59 +0530
> Jishnu Prakash <jishnu.prakash@....qualcomm.com> wrote:
> 
>> Add support for ADC_TM part of PMIC5 Gen3.
>>
>> This is an auxiliary driver under the Gen3 ADC driver, which implements the
>> threshold setting and interrupt generating functionalities of QCOM ADC_TM
>> drivers, used to support thermal trip points.
>>
>> Signed-off-by: Jishnu Prakash <jishnu.prakash@....qualcomm.com>
> Hi Jishnu,
> 
> A few minor things inline.
> 
> Jonathan
> 
>> diff --git a/drivers/thermal/qcom/qcom-spmi-adc-tm5-gen3.c b/drivers/thermal/qcom/qcom-spmi-adc-tm5-gen3.c
>> new file mode 100644
>> index 000000000000..c63822635f10
>> --- /dev/null
>> +++ b/drivers/thermal/qcom/qcom-spmi-adc-tm5-gen3.c
> 
>> +static int adc_tm5_register_tzd(struct adc_tm5_gen3_chip *adc_tm5)
>> +{
>> +	unsigned int i, channel;
>> +	struct thermal_zone_device *tzd;
>> +
>> +	for (i = 0; i < adc_tm5->nchannels; i++) {
>> +		channel = V_CHAN(adc_tm5->chan_props[i].common_props);
>> +		tzd = devm_thermal_of_zone_register(adc_tm5->dev, channel,
>> +						    &adc_tm5->chan_props[i],
>> +						    &adc_tm_ops);
>> +
>> +		if (IS_ERR(tzd)) {
>> +			if (PTR_ERR(tzd) == -ENODEV) {
>> +				dev_warn(adc_tm5->dev,
>> +					 "thermal sensor on channel %d is not used\n",
>> +					 channel);
>> +				continue;
>> +			}
>> +			return dev_err_probe(adc_tm5->dev, PTR_ERR(tzd),
>> +					     "Error registering TZ zone:%ld for channel:%d\n",
>> +					     PTR_ERR(tzd), channel);
>> +		}
>> +		adc_tm5->chan_props[i].tzd = tzd;
>> +		devm_thermal_add_hwmon_sysfs(adc_tm5->dev, tzd);
> 
> Can fail so unusual not to see an error check.  Add a comment if intended.
>

I just added it this way initially as I saw it was called without an error check
following it in other places in the kernel. I'll add an error check. 
 
>> +	}
>> +	return 0;
>> +}
> 
>> +
>> +static int adc_tm5_probe(struct auxiliary_device *aux_dev,
>> +			 const struct auxiliary_device_id *id)
>> +{
>> +	struct adc_tm5_gen3_chip *adc_tm5;
>> +	struct tm5_aux_dev_wrapper *aux_dev_wrapper;
>> +	struct device *dev = &aux_dev->dev;
>> +	int i, ret;
>> +
>> +	adc_tm5 = devm_kzalloc(&aux_dev->dev, sizeof(*adc_tm5), GFP_KERNEL);
> 

...

>> +	/*
>> +	 * This drvdata is only used in the function (adctm_event_handler)
>> +	 * called by parent ADC driver in case of TM violation on the first SDAM.
>> +	 */
>> +	auxiliary_set_drvdata(aux_dev, adc_tm5);
>> +
>> +	ret = devm_add_action(adc_tm5->dev, adc5_gen3_clear_work, adc_tm5);
> 
> I'd add a comment on what this is undoing as normally devm clean up matches
> something being started and there is no obvious sign of what that is here.

This is meant to cancel any existing instances of tm_handler_work scheduled
by a TM interrupt, at the time of module removal. I'll add a comment for it.

> 
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = adc_tm5_register_tzd(adc_tm5);
> 
> return adc_tm5...
> 
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
> 
>> +static int __init adctm5_init_module(void)
>> +{
>> +	return auxiliary_driver_register(&adctm5gen3_auxiliary_drv.adrv);
>> +}
>> +
>> +static void __exit adctm5_exit_module(void)
>> +{
>> +	auxiliary_driver_unregister(&adctm5gen3_auxiliary_drv.adrv);
>> +}
>> +
>> +module_init(adctm5_init_module);
>> +module_exit(adctm5_exit_module);
> 
> module_auxiliary_driver() not work for some reason?

Yes, it's because module_auxiliary_driver() relies on its input parameter
to create variable names for some of the function calls it does internally
and this goes wrong leading to compilation errors, if the input parameter
is more complex than a simple variable name.

I had described this issue earlier and you had agreed with me too, in this mail:
https://lore.kernel.org/all/20250301032901.7b38fed4@jic23-huawei/

I'll address your other comments in the next patch series.

Thanks,
Jishnu


> 
>> +
>> +MODULE_DESCRIPTION("SPMI PMIC Thermal Monitor ADC driver");
>> +MODULE_LICENSE("GPL");
>> +MODULE_IMPORT_NS("QCOM_SPMI_ADC5_GEN3");
>