Re: [PATCH] Input: Add Acer Aspire 5710 to nomux blacklist

[Vojtech Pavlik <vojtech@suse.cz>]

On Thu, Jul 10, 2014 at 09:32:16AM +0200, Hans de Goede wrote:

> >>> I also expect
> >>> that most of external PS/2 mice are dead by now, so number of cases when
> >>
> >> One would at least hope so. Sadly, internal mice and PS/2 keyboards
> >> aren't going to go away any soon, due to larger power consumption of USB
> >> devices.
> > 
> > Right, but we are not talking about mouse vs keyboard, they use separate
> > ports anyway, it is touchpad plus external PS/2 mouse case where active
> > MUX might help.
> 
> What about laptops with both a touchpad and a trackpoint ? I think in most
> cases the trackpoint works through some sort of pass-through mode of the
> touchpad (or is outright part of the touchpad ps/2 device), but are we
> sure there are no cases where the trackpoint and touchpad are really
> separate ps/2 devices hookedup through an active mux ?

I'm not aware of any current machines using active multiplexing for
that. There are basically two touchpad manufacturers: Synaptics and
ALPS. Synaptics has a nearly transparent passthrough mode and
touchpoints are connected through that. ALPS basically manufactures a
touchpad+touchpoint combo device and thus doesn't need a fully
transparent passthrough.

Active multiplexing was typically used for external PS/2 ports on
laptops, because the manufacturer couldn't anticipate the protocol of
the externally connected device.

> >>> we have users with PS/2 touchpad + external PS/2 mouse + working active
> >>> MUX is exceedingly small.
> >>>
> >>> Let's pull Vojtech in ;)
> >>
> >> What I'd prefer is to, based on DMI data, report but not enable by
> >> default Active MUX mode on any machine manufactured after a certain
> >> date. Plus have a DMI-based whitelist for machines that absolutely
> >> needed, if any are found later.
> > 
> > Looking at the changes to nomux blacklist sometimes even trying MUX
> > messes up KBC. Instead of playing date games I'd rather simply make
> > i8042.nomux default. I'm fine with having whitelist for boxes that
> > actually need and support muxing properly.
> 
> I'm a bit skeptical about making this change, see above.

I'm not too keen about it either, as it could break existing setups. 

But I have to concede that any working hardware still using both
external and internal PS/2 and thus needing Active Multiplexing is most
likely to be found in museums today.

So the risk of breakage isn't all that big.

-- 
Vojtech Pavlik
Director SUSE Labs