Messages in this thread | | | Date | Mon, 14 Mar 2005 09:59:19 -0500 | From | Dmitry Torokhov <> | Subject | Re: [PATCH 2.6.11] IBM TrackPoint support |
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On Mon, 14 Mar 2005 08:40:22 -0500, Stephen Evanchik <evanchsa@gmail.com> wrote: > On Mon, 14 Mar 2005 13:19:56 +0100, Vojtech Pavlik <vojtech@suse.cz> wrote: > > How much does it interpret the stream in non-transparent mode? Are > > commands also passed through in soft transparent mode? > > > > I'm asking because we might want to implement a passthrough port > > similarly to what the Synaptics driver does and allow extended protocol > > mice to be connected to the external mouse port. > > I originally thought that I could implement something similar to the > Synaptics driver. Unfortunately, while in transparent mode bytes are > relayed unmodified with the TrackPoint controller disabled. In other > words, no simultaneous usage. > > That doesn't mean extended protocol mice couldn't be supported in > transparent mode however. I didn't find it particularly useful given > the TrackPoint itself would be disabled. >
Here is my take on it (now that I have skimmed the TrackPint spec) - transparent mode is to be used only when querying the external device. This way trackpoint does not interfere with data stream at all and the kernel gets a chance to know exactly whta is behing the trackpoint - Logitech, explorer, something more exotic... Once identification is done transparent mode should be cancelled.
Bit 3 can be used to de-multiplex 2 streams; hopefully trackpoint is able to rely packets longer than 3 bytes from the external device.
As far as I can see there is no point of exporting transparent mode to the userspace via sysfs. I also do not think that we need to export middle_button_disable as it is "..for compatibility with older software expecting this bit be always 0" and we do not have such an issue. Also, if we implement pass-through port, then ext_dev is also not needed since user can either unbind the driver from pass-through port or just ignore the secondary input device in his/her config.
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