Re: Test Patch: 2.5.69 Interrupt Latency

From: Alan Stern (stern@rowland.harvard.edu)
Date: Thu May 15 2003 - 16:13:40 EST


On 15 May 2003, Paul Fulghum wrote:

> 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.

My intention was to avoid resuming if the resume-detect bit is set only
on ports in an over-current condition, since that is the case mentioned in
the erratum. Of course, this isn't as failsafe as your suggestion. Which
do you think would work better?

Alan Stern

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