Messages in this thread | | | Subject | Re: Test Patch: 2.5.69 Interrupt Latency | From | Paul Fulghum <> | Date | 15 May 2003 14:42:22 -0500 |
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On Thu, 2003-05-15 at 13:11, Alan Stern wrote: > Maybe they are an Intel-specific addition? Or perhaps a more > recent version of the spec has more information -- the one I've got is 1.1 > (March 1996).
I can't find any later documents.
> Can you suggest a good way of detecting whether or not a controller is > part of a PIIX4 chipset, to indicate whether or not the OC bits are valid?
I don't see a generic way to determine the validity of these bits.
I think the PCI ID is the only way: Vendor ID 8086 Device ID 7112
The erratum is only for the PIIX4, and it is triggered only when the OC inputs are active, so limiting the check to that device should be OK.
Probably the least intrusive thing to do is to disable suspending the uhci controller if it is a PIIX4 *and* either port has an over current condition. This will catch the case of a functional USB controller that has one or more real over current conditions and the case of a deliberately disabled (by hardwiring the OC inputs) controller. The erratum will pop up in both cases causing suspend<->wake thrashing.
-- Paul Fulghum, paulkf@microgate.com Microgate Corporation, http://www.microgate.com
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