Re: Synaptics and TrackPoint problems in 2.6.12

[Sergey Vlasov <vsu@altlinux.ru>]

On Wed, Jul 20, 2005 at 10:05:13AM -0500, Dmitry Torokhov wrote:
> On 7/20/05, Sergey Vlasov <vsu@altlinux.ru> wrote:
> > Another option is to change the
> > PSMOUSE_TRACKPOINT value so that it is less than PSMOUSE_GENPS, 
> 
> No, protocol numbers should not be changed as userspace drivers/setups
> check them and rely on them being stable.

Found that now:

	psmouse->dev.id.product = psmouse->type;

So the type is visible through the input device interface.  Probably this
should be mentioned in a comment near "enum psmouse_type" - its definition
in drivers/input/mouse/psmouse.h looks just like some driver-internal
enum.

> > In theory, someone could attach a device which uses 6-byte packets to
> > the Synaptics pass-thru port; I'm not sure what would happen in this
> > case, but with Synaptics confugured for 3-byte packets (as the patch
> > below will do) this configuration even has a chance of working.
> 
> I don't think it can support more than 4 byte packets. bytes 0 and 3
> are protocol markers and can't be readily used for transmitting other
> protocols data.

At least the Synaptics protocol description mentions that its 6-byte
protocol was designed to look like two 3-byte PS/2 mouse packets, so that
it would work even if the controller looks at those markers; other such
protocols are likely to have the same property for the same reason.  Now,
if the Synaptics touchpad would be able to accept a 6-byte packet from the
pass-thru port as two 3-byte packets...

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