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    SubjectRe: 2.4.22 USB problem (uhci)
    >>>>> "Jan" == Jan Rychter <>:
    >>>>> "Greg" == Greg KH <> writes:
    Jan> [...]

    > Please allow me to restate the original problem:
    > -- I usually use uhci instead of usb-uhci, because it is able to go
    > into "suspend mode" when no devices are plugged, which allows the CPU
    > to enter C3 states,
    > -- usb-uhci eats CPU power by keeping it in C2 constantly because of
    > busmastering DMA activity, therefore being much less useful,
    > -- uhci generally works for me just fine, but breaks in one
    > particular case, when removing the device causes a strange message to
    > be printed and the system being unable to use the C3 states again,
    > until uhci is unloaded and reloaded back again.
    > Just as a reminder, this message is:
    > uhci.c: efe0: host controller halted. very bad
    > I hope if the message says "very bad", then this is something that
    > can be fixed. I was therefore reporting a problem with "uhci" and
    > kindly asking for help.

    Greg> Ok, sorry for the confusion. No I don't know of a fix for this
    Greg> problem, but one just went into the 2.6 kernel tree for the
    Greg> uhci-hcd driver that you might want to take a look at that fixed
    Greg> a problem almost exactly like this.

    Jan> Greg,

    Jan> I've looked at uhci.c, the message comes from line 2461, in
    Jan> uhci_interrupt. But there is no chance I will be able to fix it
    Jan> without first understanding thoroughly how uhci.c works.

    Jan> So I guess this goes into my "unfixed Linux bugs" bin.

    I've just realized that some people may not know why the above uhci bug
    is a problem.

    Having done some measurements and calculations, the above uhci bug
    translates into a shortened battery life: 20 minutes less for the laptop
    I've been testing on. You get 1h30 instead of 1h50 you would normally
    get if uhci would work correctly.

    That's like having only 84% of your battery available to start with.


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