Re: KVM & mouse wheel

[Dmitry Torokhov]

Hi,

On Tuesday 03 August 2004 10:26 am, Marko Macek wrote:
> Hello!
> 
> A few months ago I posted about problems with 2.6 kernel, KVM and mouse
> wheel.
> 
> I was using 2.4 kernel until recently, but with the switch to FC2 with
> 2.6 kernel this problem became much more annoying.
> 
> My mouse is Logitech MX 510.
> 
> I figured out a few things.
> 
> 1. Trying to set the mouse/kvm into a stream mode makes things insane.
> Since streaming mode is supposed to be the default, I propose not
> doing this at all. I haven't researched this further.
> 
> -      psmouse_command(psmouse, param, PSMOUSE_CMD_SETSTREAM);

Could you describe what insane mean? If you take the KVM out of the picture
is the mouse still instane?

> 
> 2. synaptics_detect hoses imps and exps detection. Resetting the mouse
> after failed detect fixes it. This makes 'imps' and 'exps' protocols
> work when used as proto=imps or proto=exps. Wheel works, I haven't tried
> the buttons.
> 

Again, does it work without the KVM?

> 3. PS2++ detection correctly detects Logitech MX mouse but doesn't
> enable the PS2PP protocol, because of unexpected results in this code:
> 
> 	param[0] = param[1] = param[2] = 0;
>          ps2pp_cmd(psmouse, param, 0x39); /* Magic knock */
>          ps2pp_cmd(psmouse, param, 0xDB);
> 
>          if ((param[0] & 0x78) == 0x48 &&
>              (param[1] & 0xf3) == 0xc2 &&
>              (param[2] & 0x03) == ((param[1] >> 2) & 3)) {
>                  ps2pp_set_smartscroll(psmouse);
> 	        protocol = PSMOUSE_PS2PP;
>          }
> 
> The returned param array in my case is: 08 01 00 or 08 00 00 (hex)
> (without KVM: C8 C2 64)
> 
> I don't understand what this code is trying to check or why the protocol
> is only set conditionally. If I set it unconditionally (swap last 2
> lines) the PS2++ protocol now works including detection of all buttons
> (I don't really need the buttons, just the wheel).
> 

Apparently your KVM doctors the data stream from the mouse. The driver
tries to play safe and only switches to PS2++ protocol if mouse responds
properly, otherwise there is a chance that it uses PS2++ with mouse that
does not actually support it. 

> This is not included in the patch. The alternative solution
> is to reset the mouse again and resume probing for imps or exps.
> 

It will be probed for imps/exps if PS2++ fails. Now I suspect that your
particular KVM does not expect any extended probes and gets confused by
them.

-- 
Dmitry
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