Re: [PATCH] make psaux reconnect adjustable

[Gunther.Mayer@t-online.de (Gunther Mayer)]

Andries.Brouwer@cwi.nl wrote:
> 
>     From garloff@garloff.de Tue Aug 14 11:57:23 2001
> 
>     I can confirm what you suggest:
>         My mouse (Logitech wheel USB/PS2) sends indeed AA 00.
>     So, I extended my patch:
>     psmouse_reconnect = 0: Do nothing (just pass all to userspace)
>     psmouse_reconnect = 1: Flush Q & ping mouse on AA 00 (default)
>     psmouse_reconnect = 2: Flush Q & ping mouse on AA (old behaviour)
> 
>     With reconnect 1 or 2: After reconnecting, mouse behaves strange
>         (jumping around the screen)

This is a serious bug in many user-space drivers. PS/2 mouse protocol
was designed to easily re-synchronize (think about transmission errors/
lost bytes).

>     With reconnect 0:      Mouse is dead

This is a bug in all user-space drivers (understandable as the
kernel tried to be too clever). They must send the proper ps2-enabling
sequence after they see "aa 00".

> 
>     In both cases restarting gpm gets the mouse back to work again.
>     It seems the imps2 driver does some initialization to the mouse.
> 
>     If I use the plain ps2 driver, then finally, I see the benefit of the
>     reconnect code in the kernel:
>     With reconnect = 1 or 2: It works after replugging
>     With reconnect = 0:      Mouse is dead after replugging
> 
>     In the latter case restarting gpm helps.
...

Add an "ioctl(PS2_TRANSPARENT)", to disable the current kernel policy.
So new drivers which understand about "aa 00" sequences can act properly.
Don't break existing apps.