On Mon 2018-06-18 01:28:58, Tony Lindgren wrote:

* Pavel Machek [off-list ref] [180618 07:43]:

quoted

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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