> 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.pall...@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
