linux-kernel - Re: [PATCH v5 2/2] hwmon: scmi: Scale values to target desired HWMON units

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Message-ID: <2cbed0ac-fbfc-e66e-7cb9-908478466a34@gmail.com>
Date:   Tue, 14 May 2019 09:44:02 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Sudeep Holla <sudeep.holla@....com>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-arm-kernel@...ts.infradead.org,
        "open list:HARDWARE MONITORING" <linux-hwmon@...r.kernel.org>
Subject: Re: [PATCH v5 2/2] hwmon: scmi: Scale values to target desired HWMON
 units

On 5/14/19 9:37 AM, Sudeep Holla wrote:
> On Wed, May 08, 2019 at 11:46:35AM -0700, Florian Fainelli wrote:
>> If the SCMI firmware implementation is reporting values in a scale that
>> is different from the HWMON units, we need to scale up or down the value
>> according to how far appart they are.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
>> ---
>>  drivers/hwmon/scmi-hwmon.c | 45 ++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 45 insertions(+)
>>
>> diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
>> index a80183a488c5..2c7b87edf5aa 100644
>> --- a/drivers/hwmon/scmi-hwmon.c
>> +++ b/drivers/hwmon/scmi-hwmon.c
>> @@ -18,6 +18,47 @@ struct scmi_sensors {
>>  	const struct scmi_sensor_info **info[hwmon_max];
>>  };
>>  
>> +static inline u64 __pow10(u8 x)
>> +{
>> +	u64 r = 1;
>> +
>> +	while (x--)
>> +		r *= 10;
>> +
>> +	return r;
>> +}
>> +
>> +static int scmi_hwmon_scale(const struct scmi_sensor_info *sensor, u64 *value)
>> +{
>> +	s8 scale = sensor->scale;
>> +	u64 f;
>> +
>> +	switch (sensor->type) {
>> +	case TEMPERATURE_C:
>> +	case VOLTAGE:
>> +	case CURRENT:
>> +		scale += 3;
>> +		break;
>> +	case POWER:
>> +	case ENERGY:
>> +		scale += 6;
>> +		break;
>> +	default:
>> +		break;
>> +	}
>> +
> 
> I was applying this and wanted to check if we can add a check for scale=0
> here and return early here to above the below check and __pow10(0) ?

Doing an early check for scale == 0 sounds like a good idea,good catch!
Feel free to amend the patch directly when you apply it.

> 
> Let me know if you agree. I can fix up. Also I will try to test it on
> Juno if firmware behaves correctly :)

Great, thanks.
-- 
Florian