Comment 21 for bug 381884

Ahhh, that makes so much sense. Thanks for the input Ricky. It would be
helpful to look at bcm5974 to see what the deal is.

Blaine

On Wed, Apr 14, 2010 at 9:04 AM, Ricky Campbell <email address hidden>wrote:

> I believe that Macbook Pro 4,1 and newer use newer hardware and thus
> have a different kernel module (bcm5974). This newer hardware make up
> the "multitouch" touchpads (i.e. can track something like 11 different
> independent touches all at once). Older hardware uses the appletouch
> driver can detect whether there is more than one finger on the touchpad,
> but do not track position data independently.
>
> Both of these hardware types (and their kernel drivers) feed data to
> Xorg through the synaptic driver.
>
> Code repos for the newer drivers can be found here:
> http://bitmath.org/code/
>
> --
> Appletouch touchpad driver produces jumpy two-fingered scrolling
> https://bugs.launchpad.net/bugs/381884
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in The Linux Kernel: New
> Status in Mactel Support: New
> Status in “xserver-xorg-input-synaptics” package in Ubuntu: Confirmed
>
> Bug description:
> Binary package hint: xserver-xorg-input-synaptics
>
> My system is: Linux richard-laptop 2.6.28-11-generic #42-Ubuntu SMP Fri Apr
> 17 01:58:03 UTC 2009 x86_64 GNU/Linux. However, this issue applies to at
> least Intrepid and Jaunty, 32 and 64 bit, running on Apple Mac hardware that
> uses an Appletouch touchpad. It has also been reported in the Gentoo and
> Debian forums.
>
> >From what I can find on the Net, the Appletouch touchpad was first used in
> February 2005 for the G4 aluminium PowerBook, and last used for the Macbook
> Pro in its 3rd generation, then 4th generation Intel Macbook in early 2008.
>
> The issue is with two-fingered scrolling. The Appletouch features the
> ability to detect two (or three) touches. OS X uses this feature to enable
> scrolling, similar to a scrollwheel on a mouse.
>
> The synaptics driver causes the simulated scrollwheel to start moving as
> soon as one places a second finger on the touchpad. That is to say, placing
> a second finger causes the trackpad driver to deliver scrolling signals,
> which means that attempts at vertical scrolling feels jumpy, or over
> sensitive.
>
> There was an update to the OS X driver that fixed this situation for Apple.
> I guess that it detects the second finger and programmatically ignores the
> first few scrollticks, thereby 'deadening' the output. This is what we
> need.
>
> The synaptics driver allows for some modification, but not for multitouch
> input. This needs to be fixed at source code level.
>
> Richard
>
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