Messages in this thread | | | Date | Sun, 24 Feb 2002 23:39:37 +0100 | From | Vojtech Pavlik <> | Subject | Re: Flash Back -- kernel 2.1.111 |
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On Mon, Feb 25, 2002 at 09:25:13AM +1100, Paul Mackerras wrote:
> Vojtech Pavlik writes: > > On Mon, Feb 25, 2002 at 09:01:06AM +1100, Paul Mackerras wrote: > > > We have some RS/6000 machines that have two separate PCI buses (two > > > host bridges) that run at 33MHz and 50MHz respectively. Fortunately > > > we also get a device tree from the firmware that tells us this. > > > > I really wonder why the 50 MHz one doesn't run at 66 MHz, and what > > Apparently the rationale is that you can put more slots on the bus > if you run it at 50MHz than you can at 66MHz.
I see. That makes sense.
> > happens if you plug in a 66MHz non-capable card to the 50 MHz bus. > > The bus speed drops to 33MHz.
Interesting. I'd expect 25 myself ... then we'll definitely need two clock values in struct pci_bus - because the hi-speed one isn't always a double the low one - as shown by your example.
-- Vojtech Pavlik SuSE Labs - 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/
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