Synaptics driver on XO-1.5 hw?

[C. Scott Ananian]

On Thu, Oct 28, 2010 at 11:01 PM, Daniel Drake <dsd at laptop.org> wrote:
> On 28 October 2010 15:54, Martin Langhoff <martin.langhoff at gmail.com> wrote:
>> On XO-1, we have a long painful history with synaptics and the EC,
>> that's led to it being disabled. Instead we use the PS2 protocol.
>>
>> I just realised that we still do that on XO-1.5 on F11 and F14 builds,
>> and can't find commentary from anyone trying anything different.
>>
>> Are there reasons to think Synaptics may now work?
>
> As far as I know there is still no explanation nor diagnosis for the
> super-strange EC behaviour in this mode. I don't know if anyone has

IIRC (and it's been a long time, so don't trust me on this) the
Synaptics PS/2 protocol involves more 'context' than the standard
mouse packet format, making it more likely that dropped PS/2 bytes
could lead to desynchronization (and Bad Mousing).  If the underlying
PS/2 bus code is more reliable on XO-1.5, I'd expect that Synaptics
might be fine again.

FWIW, careful about the distinction between the "Synaptics PS/2
protocol" (since there are USB versions), the "Synaptics driver in the
kernel", which converts that protocol to evdev, and the "Synaptics X
driver" which is actually hardware agnostic and just translate generic
evdev messages into X events, handling edge scrolling and other nice
touchpad features. (Although on non-evdev platforms I understand that
the "Synaptics X driver" does contain code to parse the "Synaptics
PS/2 protocol".)

I highly recommend using the Synaptics X driver.  I don't know enough
about the XO-1.5 hardware to say whether you should be using the
Synaptics PS/2 protocol.
  --scott

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