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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/7/19 6:55 AM, Guenter Roeck wrote: > Hi Florian, > > On 5/6/19 3:41 PM, 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 >> --- >>   drivers/hwmon/scmi-hwmon.c | 55 +++++++++++++++++++++++++++++++------- >>   1 file changed, 46 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c >> index a80183a488c5..e9913509cb88 100644 >> --- a/drivers/hwmon/scmi-hwmon.c >> +++ b/drivers/hwmon/scmi-hwmon.c >> @@ -18,6 +18,51 @@ struct scmi_sensors { >>       const struct scmi_sensor_info **info[hwmon_max]; >>   }; >>   +static enum hwmon_sensor_types scmi_types[] = { >> +    [TEMPERATURE_C] = hwmon_temp, >> +    [VOLTAGE] = hwmon_in, >> +    [CURRENT] = hwmon_curr, >> +    [POWER] = hwmon_power, >> +    [ENERGY] = hwmon_energy, >> +}; >> + >> +static u64 scmi_hwmon_scale(const struct scmi_sensor_info *sensor, >> u64 value) >> +{ >> +    u64 scaled_value = value; > > I don't think that variable is necessary. > >> +    s8 desired_scale; > > Just scale ? Also, you could assign scale here directly, and subtract > the offset below. Then "n" would not be necessary. > Such as >     s8 scale = sensor->scale;    // assuming scale is s8 >     ... >     case CURRENT: >         scale += 3; >     ... > > That would also be less confusing, since it would avoid the double > negation. > >> +    int n, p; > >> + >> +    switch (sensor->type) { >> +    case TEMPERATURE_C: >> +    case VOLTAGE: >> +    case CURRENT: >> +        /* fall through */ > Unnecessary comment Is not removing the comment going to upset gcc when using -Wimplicit-fallthrough? > >> +        desired_scale = -3; >> +        break; >> +    case POWER: >> +    case ENERGY: >> +        /* fall through */ > Unnecessary comment. > >> +        desired_scale = -6; >> +        break; >> +    default: >> +        return scaled_value; > > Here we presumably want a scale of 0. However, if the scale passed > from SCMI is, say, -5 or +5, we return the original (unadjusted) > value. Seems to me we would still want to adjust the value to match > hwmon expectations. Am I missing something ? You raise a valid point, not that could happen today because if the sensor type has a value we don't recognize, we have not registered it, so we would not even try to read rom it, but let's be future proof. > >> +    } >> + >> +    n = (s8)sensor->scale - desired_scale; >> +        if (n == 0) > > Indentation seems off here. > >> +                return scaled_value; >> + >> +    for (p = 0; p < abs(n); p++) { >> +        /* Need to scale up from sensor to HWMON */ >> +        if (n > 0) >> +            scaled_value *= 10; >> +        else >> +            do_div(scaled_value, 10); >> +    } > > Something like > >     factor = pow10(abs(scale)); >     if (scale > 0) >         value *= factor; >     else >         do_div(value, factor); > > would avoid the repeated abs() and do_div(). Unfortunately there is > no pow10() helper, so you would have to write that. Still, I think > that would be much more efficient. Sounds reasonable. Thanks for your feedback! -- Florian