On Sun, Oct 4, 2009 at 6:45 PM, Henrique de Moraes Holschuh <hmh@xxxxxxxxxx> wrote: > On Sun, 04 Oct 2009, Miguel Ojeda wrote: >> Some broken batteries like my DELL NR2227 or a friend's DELL GK4798 return >> the design_capacity (charge_full_design) as capacity_now (charge_now) >> when completely charged. >> >> I noticed this when looking at a battery plugin that reported "127% charged". >> Some of these plugins have already "fixed" this in userspace by coding >> something like min(percentage, 100)). > > A battery can be charged above 100%. It just depends what you call 100%, > and the "I am full" level *varies* in a non-monotonic way during the battery > lifetime... > > So, if you don't want to see > 100%, you have to clamp it to 100% and lose > information (when your "100%" level is actually increasing as the thing > keeps charging and you keep raising the baseline so that it doesn't go over > 100%). If the 100% level increased, then full_charge_capacity (a.k.a. "_last_ full capacity" as seen in /proc) will increase as well, won't it? If the battery went over that 100% that means there is a "new" 100%, why are we losing information?. I am asking, I am not an expert on battery stuff. > >> So I discovered that the battery wrongly returns charge_full_design when >> completely charged instead of charge_full. > > Ick. > >> This patch fixes this by returning min(capacity_now, full_charge_capacity) >> on both procfs and sysfs. > > What will it cause on non-broken batteries? Or during gauge reset, when any > battery that updates full_charge_capacity only at the end of the cycle will > really have capacity_now > full_charge_capacity ? Well, does it make sense to have capacity_now higher than full_charge_capacity? Wouldn't that information be broken too? Again, I am just wondering. > >> Now the userspace plugins report the correct 100% and their userspace check >> may not be needed (if this error is the only one producing >100% results). > > Like I said, > 100% can happen, unless what you define to be 100% is very > elastic (and gets updated all the time). I still think it does not make sense to have a battery charged over its 100% capacity whatever the definition of 100% is. Maybe I do not understand your point. > > -- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
