Am 17.03.2015 um 09:47 schrieb Pavel Machek <pa...@ucw.cz>: > Hi! > >>>> diff --git >>>> a/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt >>>> b/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt >>>> new file mode 100644 >>>> index 0000000..bb3580c >>>> --- /dev/null >>>> +++ >>>> b/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt >>>> @@ -0,0 +1,43 @@ >>>> +twl4030_madc_battery >>>> + >>>> +Required properties: >>>> + - compatible : "ti,twl4030-madc-battery" >>>> + - capacity-uah : battery capacity in uAh >>> >>> Could we make it capacity-uAh ? >> This name was suggested by Mark Rutland [1] and naming convention >> should be all lowercase. There exists already bindings >> without uppercase (e.g. ti,bb-uamp) so I would keep it consistent. > > Messing up SI units due to "convention" is _stupid_. Don't do it. > >>> to introduce coefficients for temperature and discharge rate? >> What do you mean? Nothing like that is used in current driver why do >> we need to add it? > > Well, conversion between Li-ion's voltage and state of charge at 0 > current is well known: > > def percent(m, v): > u = 0.0387-(1.4523*(3.7835-v)) > if u < 0: > return 0 > return (0.1966+math.sqrt(u))*100
I forgot to ask: does the kernel have a sqrt() function? > > And there's not much to calibrate there, and it should become library > helper function; there's no need to write it to every single dts. > > The charge/discharge difference is due to internal battery resistance, > and Ohm's law. (Then, you should not need different values for > charging/discharging case.) > > With your aproach, you'll get lower percentage when phone is under > load vs. idle. Taking internal resistance into account would give you > more precise readings. (Attached, old patch for zaurus shows the > needed computation). > > And if you wanted even more precise readings... internal resistance > depends on temperature. > > I guess this should go into library somewhere, because many machines > need similar code. > > Pavel > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) > http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > <zbattery.10.diff> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
