linux-kernel - Re: [PATCH 13/40] hwmon: (lm90) Support multiple temperature resolutions

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Message-ID: <a1760694-7ac7-3f31-c181-13f663bd60b0@roeck-us.net>
Date:   Thu, 26 May 2022 07:32:09 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Slawomir Stepien <sst@...zta.fm>
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jean Delvare <jdelvare@...e.com>
Subject: Re: [PATCH 13/40] hwmon: (lm90) Support multiple temperature
 resolutions

On 5/26/22 00:12, Slawomir Stepien wrote:
> On maj 25, 2022 06:57, Guenter Roeck wrote:
>> (...)
>> @@ -1477,36 +1332,36 @@ static int lm90_temp_write(struct device *dev, u32 attr, int channel, long val)
>>   
>>   	switch (attr) {
>>   	case hwmon_temp_min:
>> -		if (channel == 0)
>> -			err = lm90_set_temp8(data,
>> -					      lm90_temp_min_index[channel],
>> -					      val);
>> -		else
>> -			err = lm90_set_temp11(data,
>> -					      lm90_temp_min_index[channel],
>> -					      val);
>> +		err = lm90_set_temp(data, lm90_temp_min_index[channel],
>> +				    channel, val);
>>   		break;
>>   	case hwmon_temp_max:
>> -		if (channel == 0)
>> -			err = lm90_set_temp8(data,
>> -					     lm90_temp_max_index[channel],
>> -					     val);
>> -		else
>> -			err = lm90_set_temp11(data,
>> -					      lm90_temp_max_index[channel],
>> -					      val);
>> +		err = lm90_set_temp(data, lm90_temp_max_index[channel],
>> +				    channel, val);
>>   		break;
>>   	case hwmon_temp_crit:
>> -		err = lm90_set_temp8(data, lm90_temp_crit_index[channel], val);
>> +		err = lm90_set_temp(data, lm90_temp_crit_index[channel],
>> +				    channel, val);
>>   		break;
>>   	case hwmon_temp_crit_hyst:
>>   		err = lm90_set_temphyst(data, val);
>>   		break;
>>   	case hwmon_temp_emergency:
>> -		err = lm90_set_temp8(data, lm90_temp_emerg_index[channel], val);
>> +		err = lm90_set_temp(data, lm90_temp_emerg_index[channel],
>> +				    channel, val);
>>   		break;
>>   	case hwmon_temp_offset:
>> -		err = lm90_set_temp11(data, REMOTE_OFFSET, val);
>> +		val = lm90_temp_to_reg(0, val,
>> +				       lm90_temp_get_resolution(data, REMOTE_OFFSET));
>> +		data->temp[REMOTE_OFFSET] = val;
> 
> I do not understand why you do this val assignment here, before doing real i2c write. That write
> might fail and then we have "incorrect" value in data->temp.
> 

No special reason. I'll move the assignment to the end of the case statement.

Guenter

>> +		err = i2c_smbus_write_byte_data(data->client,
>> +						LM90_REG_REMOTE_OFFSH,
>> +						val >> 8);
>> +		if (err)
>> +			break;
>> +		err = i2c_smbus_write_byte_data(data->client,
>> +						LM90_REG_REMOTE_OFFSL,
>> +						val & 0xff);
>>   		break;
>>   	default:
>>   		err = -EOPNOTSUPP;
>> @@ -2035,6 +1890,7 @@ static int lm90_probe(struct i2c_client *client)
>>   	 * ALERT# output
>>   	 */
>>   	data->alert_alarms = lm90_params[data->kind].alert_alarms;
>> +	data->resolution = lm90_params[data->kind].resolution ? : 11;
>>   
>>   	/* Set chip capabilities */
>>   	data->flags = lm90_params[data->kind].flags;
>