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    SubjectRe: kbd not functioning in 2.5.25-dj2
    On Sun, Jul 14, 2002 at 02:17:31PM +0200, Andries Brouwer wrote:
    > On Sun, Jul 14, 2002 at 02:01:53PM +0200, Vojtech Pavlik wrote:
    >
    > > > mice: PS/2 mouse device common for all mice
    > > > atkbd.c: Sent: f5
    > > > atkbd.c: Received fe
    > > > serio: i8042 KBD port at 0x60,0x64 irq 1
    > >
    > > Ok. So this is the cause. The driver gets a '0xfe' response, which means
    > > "error, command not supported, or device not present'.
    > >
    > > A keyboard must support the 0xf5 command ('reset').
    >
    > I have not followed the discussion and probably say something
    > entirely out of context. But from the good old days I seem to
    > recall commands 0xff "reset", 0xf5 "set defaults and deactivate"
    > and reply 0xfe "please resend".
    >
    > In principle nothing is wrong when one gets a 0xfe.
    > The request is just: please say that again.

    Commands:

    0xf5 - n/a - Keyboard
    Reset and disable keyboard. The keyboard performs a reset to a power
    on state (without affecting the LEDs) and stops generating events.

    0xff - 1*R - Keyboard / Mouse
    Reset and perform the Basic Assurance Test (BAT). Device returns a
    BAT completion code 0xaa. If it's a keyboard, then switches to scancode
    set 2. If it's a mouse, it also sends 0x00, 0x03 or 0x04 after 0xaa.
    Since BAT is also triggered on power-on, a device will send 0xaa
    immediately after being plugged in.

    Responses:

    0xfe
    Resend. Keyboard will send this if it didn't receive the last command
    correctly.

    Unfortunately, 0xfe also happens when you send a command to a keyboard
    that's not plugged, or when the keyboard doesn't understand the command.
    Resending in those cases (which are the most common) would cause an
    infinite loop ...

    --
    Vojtech Pavlik
    SuSE Labs
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