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    SubjectRe: i8042 access timings
    On Thu, Jan 27, 2005 at 09:29:47PM +0100, Andries Brouwer wrote:

    > > So what _might_ happen is that we write the command, and then
    > > i8042_wait_write() thinks that there is space to write the data
    > > immediately, and writes the data, but now the data got lost because the
    > > buffer was busy.
    > Hmm - I just answered the same post and concluded that I didnt understand,
    > so you have progressed further. I considered the same possibility,
    > but the data was not lost since we read it again later.
    > Only the ready flag was lost.

    What I believe is happening is that we're talking to SMM emulation of
    the i8042, which doesn't have a clue about these commands, while the
    underlying real hardware implementation does. And because of that they
    disagree on what should happen when the command is issued, and since the
    SMM emulation lazily synchronizes with the real HW, we only get the data
    back with the next command.

    I still don't have an explanation why both 'usb-handoff' and 'acpi=off'
    help, I'd expect only the first to, but it might be related to the SCI
    interrupt routing which isn't done when 'acpi=off'. Just a wild guess.

    Vojtech Pavlik
    SuSE Labs, SuSE CR
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