Re: [ltp] Re: [PATCH v2] Re: Battery class driver.

[Bill Davidsen <davidsen@tmr.com>]

Henrique de Moraes Holschuh wrote:
> On Wed, 01 Nov 2006, Greg KH wrote:
> > On Wed, Nov 01, 2006 at 09:53:12PM +0200, Shem Multinymous wrote:
> > > Hi Greg,
> > >
> > > On 11/1/06, Greg KH <greg@kroah.com> wrote:
> > > > > The suggestions so far were:
> > > > > 1. Append units string to the content of such attribute:
> > > > >   /sys/.../capacity_remaining reads "16495 mW".
> > > > > 2. Add a seprate *_units attribute saying what are units for other
> > > > > attribute:
> > > > >   /sys/.../capacity_units gives the units for
> > > > >   /sys/.../capacity_{remaining,last_full,design,min,...}.
> > > > > 3. Append the units to the attribute names:
> > > > >   capacity_{remaining,last_full,design_min,...}:mV.
> > > > No, again, one for power and one for current.  Two different files
> > > > depending on the type of battery present.  That way there is no need to
> > > > worry about unit issues.
> > > I'm missing something. How is that different from option 3 above?
> > No silly ":mV" on the file name.
>
> As long as that also means no "silly _mV" in the name.  However, if the
> choice is between :mV and _mV, please go with :mV.
>
> > > BTW, please note that we're talking about a large set of files that
> > > use these units (remaining, last full, design capacity, alarm
> > > thresholds, etc.), and not just a single attribute.
> > Sure, what's wrong with:
> > 	capacity_remaining_power
> > 	capacity_last_full_power
> > 	capacity_design_min_power
> > if you can read that from the battery, and:
> > 	capacity_remaining_current
> > 	capacity_last_full_current
> > 	capacity_design_min_current
> > if you can read that instead.
>
> Well, "Wh" measures energy and not power, and "Ah" measures electric charge
> and not current, so it would be better to make that:
>
> capacity_*_energy  (Wh-based)
>
> and
>
> capacity_*_charge  (Ah-based)
>
> Also, should we go with mWh/mAh, or with even smaller units because of the
> tiny battery-driven devices of tomorrow?
Having seen a French consultant with a Windows laptop reporting mJ 
(Joules) I bet that came from the hardware. And given that laptop 
batteries run at (almost) constant voltage, could all of these just be 
converted to mWh for consistency?

--
Bill Davidsen <davidsen@tmr.com>
  Obscure bug of 2004: BASH BUFFER OVERFLOW - if bash is being run by a
normal user and is setuid root, with the "vi" line edit mode selected,
and the character set is "big5," an off-by-one errors occurs during
wildcard (glob) expansion.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/