Re: usbhid: HP LD4200tm touchscreen ALMOST works

From: William Sherman
Date: Tue Nov 02 2010 - 09:46:35 EST


On 11/1/10 5:22 PM, Jiri Kosina wrote:
On Mon, 1 Nov 2010, Dmitry Torokhov wrote:

I'm looking to dig into the usbhid driver code to get me the last
mile and get my HP LD4200tm touchscreen working on my Linux system.
[NOTE: I posted about this elsewhere, but as I think about it more,
this is more of a linux-kernel issue than anything else, so I'm
reprising that note here.]

I think you'll have better luck on linux-input...

Thanks for CC, Dmitry.

Yes, thanks from me too for pointing this thread in the right direction.
I also sent a revised (updated) post to the linux-kernel list, but was
not aware of the linux-input list.

Thanks a lot for the detailed analysis. What would actually be interesting
to see would be the HID debugfs output. Namely

1) mount debugfs
2) cat /sys/kernel/debug/<device>/rdesc
3) obtain output of /sys/kernel/debug/<device>/events and annotate it as
you did for your previous output (i.e. "this happens when I do one-finger
move", "this happens when I do two-finger trick to make it work").

This way, it'd be much easier to see what is actually hapenning on HID
level.

Great. I will do that as soon as I can -- which is when I arrive at
SuperComputing to setup our system. The display (our only one) is currently
on a truck bound for New Orleans.

In the meantime, I wrote a very simple application that parses the
data directly from /dev/hidrawN, does a simple parse, and then
creates X events with the Xtest API. Of course, I'm only doing
single touch, since that's all I need for the moment.

I also have a Dell SX2210T touch screen with the NextWindow interface.
We made some partial progress on our Ubuntu 10.10 system with the nwfermi
driver, but again, not quite all the way -- of course now that computer
is on the road, and I'm not having as much luck with that touchscreen
on my Fedora 13 system.

Thanks,

Thank you both, and more to come,
Bill

--
Bill Sherman
Sr. Technology Advisor
Advanced Visualization Lab
Pervasive Technologies Inst
Indiana University
shermanw@xxxxxxxxxxx

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