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

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Date:   Tue, 14 May 2019 09:58:06 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Sudeep Holla <sudeep.holla@....com>, linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        Jean Delvare <jdelvare@...e.com>,
        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 Tue, May 14, 2019 at 09:44:02AM -0700, Florian Fainelli wrote:
> 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.
> 

Ok with me. Just make it == 0 :-).

Guenter

> > 
> > 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