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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.


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.


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

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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