Messages in this thread | | | From | "Pallala, Ramakrishna" <> | Subject | RE: [PATCH] max17042_battery: add support for battery STATUS and CHARGE_TYPE | Date | Wed, 15 Aug 2012 02:28:41 +0000 |
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> On Fri, Jul 27, 2012 at 10:26:21PM +0530, Ramakrishna Pallala wrote: > > This patch adds the support to report the battery power supply > > attributes STATUS and CHARGE_TYPE. This patch makes use of > > power_supply_get_external_attr() API to get these attributes through power > supply core. > > > > Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com> > > --- > [...] > > switch (psp) { > > + case POWER_SUPPLY_PROP_STATUS: > > + ret = power_supply_get_external_attr(&query); > > + if (ret < 0) > > + return ret; > > + val->intval = query.res.intval; > > + break; > > First of, thanks a lot for your work. And sorry that it took me quite a while to > review it, but these are fundamental changes, so I had to thoughtfully consider > all this. > > This exact code clearly shows that it is not battery's property. Battery itself > cannot report it, right? OK, here is what > Documentation/power/power_supply_class.txt says: > > A: Most likely, no. This class is designed to export properties which are > directly measurable by the specific hardware available. > > Inferring not available properties using some heuristics or mathematical > model is not subject of work for a battery driver. Such functionality > should be factored out > > So, you basically try to infer battery's properties from the charger hw. > This is surely doable, but no, I think we should not do this. Instead, what we > want is to make use of "supplied_to" mechanism of the power supply class, and > export it via sysfs. Then userland can see all the power supply hierarchy, and > thus see which hardware provides which data. > > See my thoughts about exporting "supplied_to" to the sysfs: > > http://lkml.org/lkml/2011/6/22/258 > > So, we'll have: > > /sys/ > class/ > power_supply/ > charger/ > supplied_to/battery -> ../../battery > battery/ > > Sure, we'll have to teach userland to operate on this scheme, i.e. > it must be aware that batteries might be connected to an external charger, and > if so, userland must query* charging status from the charger. > > Do you see any problem with this approach? > > Thanks!
Got your point. I will try this approach. Thanks for your time :-)
Thanks, Ram
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