On Mon 2018-06-18 01:28:58, Tony Lindgren wrote:
> * Pavel Machek <pavel@xxxxxx> [180618 07:43]:
> >
> > So... there are mA, mAh values. Those come from hardware, and I
> > believe we should keep them.
> >
> > But there are also mW, mWh values, which are synthetic. Userland can
> > compute them from mV, mA values... and it is confusing that kernel
> > provides them. (My tendency was to start computing these synthetic
> > values in userland, to compare them with "real hardware" values from
> > kernel. But then I looked at kernel implementation, and realized they
> > are synthetic, tooo...)
>
> Hmm mWh value is based on the hardware sampled shunt
> values and number of samples gathered between the
> two readings. I'd rather call the calculated values
> based on userland reading mV and mA values "synthetic" :)
As far as I know, shunt resistors provide you with current (mA) not
power (mW) measurement... and cpcap-battery computes power_now as
voltage * current. I'd rather have kernel tell me "hardware can't
measure power" and do "voltage*current" computation in userspace.
So I'm proposing to apply patch below.
Best regards,
Pavel
+++ b/drivers/power/supply/cpcap-battery.c
@@ -490,24 +490,6 @@ static int cpcap_battery_get_property(struct power_supply *psy,
case POWER_SUPPLY_PROP_CHARGE_COUNTER:
val->intval = latest->counter_uah;
break;
- case POWER_SUPPLY_PROP_POWER_NOW:
- tmp = (latest->voltage / 10000) * latest->current_ua;
- val->intval = div64_s64(tmp, 100);
- break;
- case POWER_SUPPLY_PROP_POWER_AVG:
- if (cached) {
- tmp = cpcap_battery_cc_get_avg_current(ddata);
- tmp *= (latest->voltage / 10000);
- val->intval = div64_s64(tmp, 100);
- break;
- }
- sample = latest->cc.sample - previous->cc.sample;
- accumulator = latest->cc.accumulator - previous->cc.accumulator;
- tmp = cpcap_battery_cc_to_ua(ddata, sample, accumulator,
- latest->cc.offset);
- tmp *= ((latest->voltage + previous->voltage) / 20000);
- val->intval = div64_s64(tmp, 100);
- break;
case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
if (cpcap_battery_full(ddata))
val->intval = POWER_SUPPLY_CAPACITY_LEVEL_FULL;
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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