[LAD] Timers, hpet, hrtimer

[fons at kokkinizita.net]

On Tue, Nov 10, 2009 at 09:34:28PM +0200, Jussi Laako wrote:

> fons at kokkinizita.net wrote:
> > So you're just reading it, not waiting on it ? That indeed
> > should be 'free'. 
> 
> Yes, we just need to read it. JACK used to use TSC for that, and HPET
> support was introduced as similar low-cost alternative to deal with
> variable clock frequencies (important on mobile things) and unsynced
> TSC. Use of syscalls is kind of fallback.
> 
> Audio hardware (interrupts) act as a waitable time source.

All perfectly logical. But what then is stopping the driver devs
from providing just read access to the main counter ? Who could
object to read-only access to a device register (if reading it
has no side effects) ?
 
Ciao,

-- 
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.