linux-kernel - Re: [PATCH v3 2/2] hwmon: Support set

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Message-ID: <f3ea4b2d-ee84-6e28-5136-276163369497@gmail.com>
Date:   Mon, 21 Jun 2021 23:45:36 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH v3 2/2] hwmon: Support set_trips() of thermal device ops

21.06.2021 23:30, Guenter Roeck пишет:
> On Mon, Jun 21, 2021 at 09:40:58PM +0300, Dmitry Osipenko wrote:
>> Support set_trips() callback of thermal device ops. This allows HWMON
>> device to operatively notify thermal core about temperature changes, which
>> is very handy to have in a case where HWMON sensor is used by CPU thermal
>> zone that performs passive cooling and emergency shutdown on overheat.
>> Thermal core will be able to react faster to temperature changes.
>>
> 
> I think that warrants an explanation why it doesn't matter if the
> code doesn't really set any trip points.

I'll extend the commit message.

>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/hwmon/hwmon.c | 32 ++++++++++++++++++++++++++++++++
>>  1 file changed, 32 insertions(+)
>>
>> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
>> index fd47ab4e6892..e74dc81e650d 100644
>> --- a/drivers/hwmon/hwmon.c
>> +++ b/drivers/hwmon/hwmon.c
>> @@ -153,8 +153,40 @@ static int hwmon_thermal_get_temp(void *data, int *temp)
>>  	return 0;
>>  }
>>  
>> +static int hwmon_thermal_set_trips(void *data, int low, int high)
>> +{
>> +	struct hwmon_thermal_data *tdata = data;
>> +	struct hwmon_device *hwdev = to_hwmon_device(tdata->dev);
>> +	const struct hwmon_chip_info *chip = hwdev->chip;
>> +	const struct hwmon_channel_info **info = chip->info;
>> +	unsigned int i;
>> +
>> +	if (!chip->ops->write)
>> +		return 0;
>> +
>> +	for (i = 1; info[i] && info[i]->type != hwmon_temp; i++)
>> +		continue;
> 
> Why start with index 1 ? While index 0 is commonly used for chip data,
> that is not mandatory.

This is borrowed from hwmon_thermal_register_sensors().

>> +
>> +	if (info[i] && info[i]->config[tdata->index] & HWMON_T_MIN) {
>> +		int err = chip->ops->write(tdata->dev, hwmon_temp,
>> +					   hwmon_temp_min, tdata->index, low);
> 
> checkpatch will complain here because it expects an empty line after a
> declaration. Since err is used in multiple conditionals, I would suggest
> to declare it once in the function header.

Okay, although checkpatch is happy.

./scripts/checkpatch.pl --strict v3*
---------------------------------------------------------------
v3-0001-hwmon-lm90-Prevent-integer-underflows-of-temperat.patch
---------------------------------------------------------------
total: 0 errors, 0 warnings, 0 checks, 27 lines checked

v3-0001-hwmon-lm90-Prevent-integer-underflows-of-temperat.patch has no
obvious style problems and is ready for submission.
-----------------------------------------------------------
v3-0002-hwmon-Support-set_trips-of-thermal-device-ops.patch
-----------------------------------------------------------
total: 0 errors, 0 warnings, 0 checks, 40 lines checked

>> +		if (err < 0 && err != -EOPNOTSUPP)
> 
> "< 0" is unnecessary.
> 
>> +			return err;
>> +	}
>> +
>> +	if (info[i] && info[i]->config[tdata->index] & HWMON_T_MAX) {
>> +		int err = chip->ops->write(tdata->dev, hwmon_temp,
>> +					   hwmon_temp_max, tdata->index, high);
>> +		if (err < 0 && err != -EOPNOTSUPP)
> 
> "< 0" is unnecessary.

I'll remove it in v4.