Moving system timer to RTC (was Re: A/D converter)

David Woodhouse (David.Woodhouse@mvhi.com)
Wed, 21 Apr 1999 10:57:51 +0100


rhw@BigFoot.Com said:
> The obvious solution here would be to redefine the irq0 timer such
> that it runs at 18,000 Hz to perform the PC speaker stuff, and only
> calls the current irq0 routine every 180th interrupt.

> However, I would guess that latency problems would prevent that...

Not at all - that's exactly how it works at the moment. The first problem is
that it changes the frequency of the 'current irq0 routine' slightly, because
it's not exactly 'every 180th interrupt'. So it mucks up the clock accuracy.

The second problem, possibly related to the above, is that Linus doesn't
approve of such an arrangement, so while the PC speaker driver is working like
this, it's not got a chance of being included in 2.3.x. (This is hearsay - I
got that second hand at least. Confirmation would be very much appreciated,
Linus)

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