[ltp] Re: Generic battery interface

[Shem Multinymous]

On 7/29/06, Valdis.Kletnieks@vt.edu <Valdis.Kletnieks@vt.edu> wrote:
> On Sat, 29 Jul 2006 01:10:40 +0300, Shem Multinymous said:
> > On 7/28/06, Valdis.Kletnieks@vt.edu <Valdis.Kletnieks@vt.edu> wrote:
> > > Is there a reliable (or hack-worthy) way for the kernel to determine how
> > > often the values are re-posted by the hardware?
> >
> > That's hardware-specific. Some drivers can know, others may just
> > assume 1sec or 0.1sec or whatever.
>
> That smells suspiciously like "We need an API for the hardware-specific
> bits f code to pass the generic bits a value for this..." (and the
> hardware-specific part can either ask the battery, or return a
> hard-coded "10 seconds" that somebody measured, or whatever)....

I don't think "update frequency" is a good abstraction. The hardware's
update may not be variable and irrregular (e.g., event-based), and
there's there's an issue of phase sync to avoid unnecessary latency.

The lazy polling approach I described in my last post to Vojtech
("block until there's  a new readout or N milliseconds have passed,
whichever is later") looks like a more general, accurate and efficient
interface.

  Shem