> So, in first connecting the HP touchscreen (with touchscreen hardware
> from Nexio) to the Linux system (running Ubuntu 10.10 -- 2.6.35-22 generic)
> things were looking up, as the unit almost worked right out of the box
> as a plug-and-play device. Unfortunately, that last mile needs to be
> addressed in order for the unit to work in a useful way. I think I've
> narrowed down the problem to the usbhid driver, as I'll explain in a
> moment, and while I expect I have the ability to debug and fix the issue,
> this would be my first dive into Linux driver coding, so I could probably
> use a pointer as to what steps are necessary to get the proper kernel
> sources, compile the needed parts and restart the system (hopefully
> just restart X-windows) to test my edits (especially since Ubuntu tends
> to not include a not of the necessary components).
>
> I've collected gobs of data on what udev, hidraw, evtest and X-windows
> report, but before I get to any of that, here's the executive summary:
>
> Plugging the HP LD4200tm into a Ubuntu 10.10 system will cause the
> device to be recognized, create a usbhid device, create an event device,
> activate the evdev driver for Xorg, and put it on the list of X's inputs.
> So far, so good.
>
> Touching the device causes the mouse pointer to jump to that location,
> even better.
>
> But when I'm touching the screen, what happens is that the system
> generates a continuous stream of button presses/releases -- as if
> I moved the mouse to a particular location and then went crazy
> tapping on the mouse button. This is the part that makes the system
> unusable.
>
> One more data point is that if I touch the screen with a second
> finger, the button barrage stops, and it will now gracefully report
> the movement of the first finger.
>
> So all I need to do is modify the driver for this device's protocol
> to not send all the unnecessary release/press events.
>
>
> Here is the data that leads me to believe the issue is at the usbhid
> layer:
>
>
> 1) Running "evtest /dev/input/event4" reveals that the button barrage
> is already occurring at the HID event layer.
>
> 2) Watching the raw data on /dev/usb/hiddev2 does report a stream of
> data as the touchscreen is touched (and no data when it's not touched),
> looking at the output suggests that the device is only reporting touch/
> release events when the screen is actually touched or released. And of
> course, even if the device were reporting things poorly, I figure the
> usbhid driver could be written to overcome this.
>
> Fortunately, the data seems to be a constant 14-byte stride, so I
> wrote a simple awk script ("nexio") to reformat the data as I was
> figuring out the raw protocol. Here's a sample of the reformatted
> data, followed by my estimation of the protocol:
> % sudo xxd -c 14 -g 1 /dev/hidraw2 | nexio
> 0000000: 01 03 01 12d8 3357 02 02 15e1 1f71 01
> 000000e: 01 03 01 12cc 332a 02 02 15e1 1f71 01
> 000001c: 01 03 01 12de 3335 00 02 15e1 1f71 01
> 000002a: 01 03 01 12f4 3346 00 02 15e1 1f71 01
> 0000038: 01 03 01 1304 3352 00 02 15e1 1f71 01
> 0000046: 01 03 01 130c 3358 00 02 15e1 1f71 01
> [... (next I stop touching the screen, and then touch it again)]
> 00009a0: 01 03 01 12d8 3357 00 02 15e1 1f71 01
> 00009ae: 01 03 01 12d8 3357 00 02 15e1 1f71 01
> 00009bc: 01 02 01 12d8 3357 00 02 15e1 1f71 01
> 00009ca: 01 03 01 10af 3681 02 02 15e1 1f71 01
> 00009d8: 01 03 01 10a5 3651 02 02 15e1 1f71 01
> 00009e6: 01 03 01 10b7 3654 00 02 15e1 1f71 01
> [... (next is a multi-touch event)]
> 0000c78: 01 03 01 1019 3627 00 02 15e1 1f71 01
> 0000c86: 01 03 01 1019 3627 00 02 15e1 1f71 01
> 0000c94: 01 00 01 100b 35f8 00 02 1585 3110 00
> 0000ca2: 01 00 01 100e 3604 00 02 158a 311b 00
> 0000cb0: 01 00 01 1013 3615 00 02 1591 312b 00
> 0000cbe: 01 00 01 1017 3622 00 02 1596 3136 00
> 0000ccc: 01 00 01 1019 3628 00 02 1598 313c 00
> 0000cda: 01 00 01 1019 3629 00 02 1599 313d 00
> 0000ce8: 01 03 01 1019 3629 03 02 1598 313d 02
> 0000cf6: 01 03 01 1019 3628 03 02 1598 313c 02
> 0000d04: 01 03 01 1019 3627 03 02 1598 313b 02
> 0000d12: 01 03 01 1018 3627 03 02 1597 313a 02
> [... (next I release both fingers -- not quite simultaneously)]
> 0000df2: 01 03 01 1019 3627 03 02 1598 3132 02
> 0000e00: 01 03 01 1019 3627 03 02 1598 3132 02
> 0000e0e: 01 03 01 1019 3627 02 02 1598 3132 01
> 0000e1c: 01 03 01 1019 3626 02 02 1598 3132 01
> 0000e2a: 01 03 01 1019 3626 00 02 1598 3132 01
> 0000e38: 01 03 01 1019 3626 00 02 1598 3132 01
> 0000e46: 01 03 01 1019 3626 00 02 1598 3132 01
> 0000e54: 01 03 01 1019 3626 00 02 1598 3132 01
> 0000e62: 01 03 01 1019 3625 00 02 1598 3132 01
> 0000e70: 01 02 01 1019 3625 00 02 1598 3132 01
>
> Decoding the above:
> - column 1: just a reprint of the xxd byte count
> - column 2: always 01 -- probably a data packet sync byte
> - column 3: usually 03 (which means an on-going touch event)
> - 02 seems to indicate a touch-release event
> - 00 seems to indicate a transition to a dual-touch event
> - column 4: always 01 -- probably an indicator that the next two
> words are the X/Y values for touch #1
> - column 5: value of X location of touch #1
> - column 6: value of Y location of touch #1
> - column 7: usually 00
> - 02 seems to mean initiation of a single-touch event
> - 03 seems to indicate an on-going dual-touch event
> - column 8: always 02 -- probably an indicator that the next two
> words are the X/Y values for touch #2
> - column 9: value of X location of touch #2
> - column 10:value of Y location of touch #2
> - column 11: usually 01 or 02 representing the number of contact points
> - will be 00 when transitioning from single to dual
> contact touch event
>
> The rest of this email is a sample of some of the data that I've
> collected about what the system reports. I think this should be
> sufficient to get across all necessary information, but I have
> more if warrented.
>
> % xinput list --short 10
> Nexio Touch Device. HID Multi-Touch id=10
> [slave pointer (2)]
> % xinput test 10
> motion a[0]=15177 a[1]=5581 a[2]=15479 a[3]=7829 a[4]=0 a[5]=0
> motion a[6]=0 a[7]=0 a[8]=0 a[9]=0 a[10]=0
> button press 1
> button release 1
> button press 1
> button release 1
> button press 1
> button release 1
> button press 1
> button release 1
> button press 1
> button release 1
> button press 1
> button release 1
> [...]
>
> So you can see that at first contact the location of the touch is reported,
> but then there is the continual stream of button press/release.
>
> Here is the output from "evtest" from a single finger interaction:
> % sudo evtest /dev/input/event4
> Input driver version is 1.0.1
> Input device ID: bus 0x3 vendor 0x1870 product 0x100 version 0x111
> Input device name: "Nexio Touch Device. HID Multi-Touch"
> Supported events:
> Event type 0 (Sync)
> Event type 1 (Key)
> Event code 272 (LeftBtn)
> Event code 273 (RightBtn)
> Event code 274 (MiddleBtn)
> Event code 320 (ToolPen)
> Event code 321 (ToolRubber)
> Event code 322 (ToolBrush)
> Event code 330 (Touch)
> Event type 3 (Absolute)
> Event code 0 (X)
> Value 15129
> Min 0
> Max 16383
> Event code 1 (Y)
> Value 6425
> Min 0
> Max 16383
> Event code 2 (Z)
> Value 14859
> Min 0
> Max 16383
> Event code 3 (Rx)
> Value 7160
> Min 0
> Max 16383
> Event code 4 (Ry)
> Value 0
> Min 0
> Max 32767
> Event code 5 (Rz)
> Value 0
> Min 0
> Max 32767
> Event code 6 (Throttle)
> Value 0
> Min 0
> Max 16383
> Event code 7 (Rudder)
> Value 0
> Min 0
> Max 16383
> Event code 40 (Misc)
> Value 1
> Min 0
> Max 1
> Event code 41 (?)
> Value 2
> Min 0
> Max 1
> Event code 42 (?)
> Value 1
> Min 0
> Max 2
> Event type 4 (Misc)
> Event code 4 (ScanCode)
> Testing ... (interrupt to exit)
> Event: time 1287784276.760109, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.760112, type 1 (Key), code 330 (Touch), value 1
> Event: time 1287784276.760119, type 3 (Absolute), code 0 (X),
> value 14976
> Event: time 1287784276.760122, type 3 (Absolute), code 1 (Y),
> value 7291
> Event: time 1287784276.760125, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.760127, type 1 (Key), code 330 (Touch), value 0
> Event: time 1287784276.760130, type 1 (Key), code 321
> (ToolRubber), value 1
> Event: time 1287784276.760139, -------------- Report Sync ------------
> Event: time 1287784276.773107, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.773111, type 1 (Key), code 330 (Touch), value 1
> Event: time 1287784276.773117, type 3 (Absolute), code 0 (X),
> value 14925
> Event: time 1287784276.773120, type 3 (Absolute), code 1 (Y),
> value 7266
> Event: time 1287784276.773123, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.773124, type 1 (Key), code 330 (Touch), value 0
> Event: time 1287784276.773135, -------------- Report Sync ------------
> Event: time 1287784276.785094, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.785099, type 1 (Key), code 330 (Touch), value 1
> Event: time 1287784276.785105, type 3 (Absolute), code 0 (X),
> value 14937
> Event: time 1287784276.785108, type 3 (Absolute), code 1 (Y),
> value 7269
> Event: time 1287784276.785112, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784276.785113, type 1 (Key), code 330 (Touch), value 0
> Event: time 1287784276.785116, type 1 (Key), code 321
> (ToolRubber), value 0
> Event: time 1287784276.785125, -------------- Report Sync ------------
> ^C
>
> And here is the output of "evtest" from when I touched the screen with
> two fingers:
> % sudo evtest /dev/input/event4
> Input driver version is 1.0.1
> Input device ID: bus 0x3 vendor 0x1870 product 0x100 version 0x111
> Input device name: "Nexio Touch Device. HID Multi-Touch"
> Supported events:
> Event type 0 (Sync)
> Event type 1 (Key)
> Event code 272 (LeftBtn)
> Event code 273 (RightBtn)
> Event code 274 (MiddleBtn)
> Event code 320 (ToolPen)
> Event code 321 (ToolRubber)
> Event code 322 (ToolBrush)
> Event code 330 (Touch)
> Event type 3 (Absolute)
> Event code 0 (X)
> Value 14937
> Min 0
> Max 16383
> Event code 1 (Y)
> Value 7269
> Min 0
> Max 16383
> Event code 2 (Z)
> Value 14859
> Min 0
> Max 16383
> Event code 3 (Rx)
> Value 7160
> Min 0
> Max 16383
> Event code 4 (Ry)
> Value 0
> Min 0
> Max 32767
> Event code 5 (Rz)
> Value 0
> Min 0
> Max 32767
> Event code 6 (Throttle)
> Value 0
> Min 0
> Max 16383
> Event code 7 (Rudder)
> Value 0
> Min 0
> Max 16383
> Event code 40 (Misc)
> Value 1
> Min 0
> Max 1
> Event code 41 (?)
> Value 2
> Min 0
> Max 1
> Event code 42 (?)
> Value 1
> Min 0
> Max 2
> Event type 4 (Misc)
> Event code 4 (ScanCode)
> Testing ... (interrupt to exit)
> Event: time 1287784360.966997, type 1 (Key), code 320 (ToolPen),
> value 0
> Event: time 1287784360.967004, type 3 (Absolute), code 0 (X),
> value 14717
> Event: time 1287784360.967006, type 3 (Absolute), code 1 (Y),
> value 6211
> Event: time 1287784360.967014, type 3 (Absolute), code 2 (Z),
> value 15680
> Event: time 1287784360.967016, type 3 (Absolute), code 3 (Rx),
> value 6211
> Event: time 1287784360.967019, type 3 (Absolute), code 42 (?), value 0
> Event: time 1287784360.967020, -------------- Report Sync ------------
> Event: time 1287784360.979997, type 3 (Absolute), code 0 (X),
> value 14667
> Event: time 1287784360.980001, type 3 (Absolute), code 1 (Y),
> value 6189
> Event: time 1287784360.980008, type 3 (Absolute), code 2 (Z),
> value 15626
> Event: time 1287784360.980011, type 3 (Absolute), code 3 (Rx),
> value 6189
> Event: time 1287784360.980014, -------------- Report Sync ------------
> Event: time 1287784360.992997, type 3 (Absolute), code 0 (X),
> value 14684
> Event: time 1287784360.993000, type 3 (Absolute), code 1 (Y),
> value 6195
> Event: time 1287784360.993008, type 3 (Absolute), code 2 (Z),
> value 15640
> Event: time 1287784360.993011, type 3 (Absolute), code 3 (Rx),
> value 6195
> Event: time 1287784360.993014, -------------- Report Sync ------------
> Event: time 1287784361.005998, type 3 (Absolute), code 0 (X),
> value 14715
> Event: time 1287784361.006001, type 3 (Absolute), code 1 (Y),
> value 6220
> Event: time 1287784361.006008, type 3 (Absolute), code 2 (Z),
> value 15660
> Event: time 1287784361.006011, type 3 (Absolute), code 3 (Rx),
> value 6220
> Event: time 1287784361.006014, -------------- Report Sync ------------
> Event: time 1287784361.018000, type 3 (Absolute), code 0 (X),
> value 14745
> Event: time 1287784361.018004, type 3 (Absolute), code 1 (Y),
> value 6278
> Event: time 1287784361.018012, type 3 (Absolute), code 2 (Z),
> value 15674
> Event: time 1287784361.018014, type 3 (Absolute), code 3 (Rx),
> value 6278
> Event: time 1287784361.018017, -------------- Report Sync ------------
> Event: time 1287784361.030997, type 3 (Absolute), code 0 (X),
> value 14767
> Event: time 1287784361.031000, type 3 (Absolute), code 1 (Y),
> value 6358
> Event: time 1287784361.031008, type 3 (Absolute), code 2 (Z),
> value 15680
> Event: time 1287784361.031010, type 3 (Absolute), code 3 (Rx),
> value 6358
> Event: time 1287784361.031013, -------------- Report Sync ------------
> Event: time 1287784361.043996, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784361.043999, type 1 (Key), code 330 (Touch), value 1
> Event: time 1287784361.044001, type 1 (Key), code 320 (ToolPen),
> value 1
> Event: time 1287784361.044006, type 3 (Absolute), code 0 (X),
> value 14777
> Event: time 1287784361.044008, type 3 (Absolute), code 1 (Y),
> value 6451
> Event: time 1287784361.044012, type 1 (Key), code 321
> (ToolRubber), value 1
> Event: time 1287784361.044016, type 3 (Absolute), code 2 (Z),
> value 15682
> Event: time 1287784361.044019, type 3 (Absolute), code 3 (Rx),
> value 6451
> Event: time 1287784361.044021, type 3 (Absolute), code 42 (?), value 2
> Event: time 1287784361.044023, -------------- Report Sync ------------
> Event: time 1287784361.057000, type 3 (Absolute), code 0 (X),
> value 14779
> Event: time 1287784361.057004, type 3 (Absolute), code 1 (Y),
> value 6546
> Event: time 1287784361.057012, type 3 (Absolute), code 3 (Rx),
> value 6546
> Event: time 1287784361.057016, -------------- Report Sync ------------
> Event: time 1287784361.069998, type 3 (Absolute), code 0 (X),
> value 14778
> Event: time 1287784361.070001, type 3 (Absolute), code 1 (Y),
> value 6640
> Event: time 1287784361.070009, type 3 (Absolute), code 2 (Z),
> value 15681
> Event: time 1287784361.070011, type 3 (Absolute), code 3 (Rx),
> value 6640
> Event: time 1287784361.070014, -------------- Report Sync ------------
> Event: time 1287784361.081989, type 3 (Absolute), code 0 (X),
> value 14776
> Event: time 1287784361.081992, type 3 (Absolute), code 1 (Y),
> value 6733
> Event: time 1287784361.082000, type 3 (Absolute), code 2 (Z),
> value 15680
> Event: time 1287784361.082002, type 3 (Absolute), code 3 (Rx),
> value 6733
> Event: time 1287784361.082005, -------------- Report Sync ------------
> Event: time 1287784361.094987, type 3 (Absolute), code 0 (X),
> value 14775
> Event: time 1287784361.094990, type 3 (Absolute), code 1 (Y),
> value 6832
> Event: time 1287784361.094998, type 3 (Absolute), code 2 (Z),
> value 15679
> Event: time 1287784361.095000, type 3 (Absolute), code 3 (Rx),
> value 6832
> Event: time 1287784361.095004, -------------- Report Sync ------------
> Event: time 1287784361.107986, type 3 (Absolute), code 0 (X),
> value 14774
> Event: time 1287784361.107990, type 3 (Absolute), code 1 (Y),
> value 6939
> Event: time 1287784361.107999, type 3 (Absolute), code 3 (Rx),
> value 6939
> Event: time 1287784361.108002, -------------- Report Sync ------------
> Event: time 1287784361.121001, type 3 (Absolute), code 1 (Y),
> value 7042
> Event: time 1287784361.121011, type 3 (Absolute), code 3 (Rx),
> value 7042
> Event: time 1287784361.121014, -------------- Report Sync ------------
> Event: time 1287784361.132987, type 3 (Absolute), code 0 (X),
> value 14779
> Event: time 1287784361.132991, type 3 (Absolute), code 1 (Y),
> value 7138
> Event: time 1287784361.132999, type 3 (Absolute), code 3 (Rx),
> value 7138
> Event: time 1287784361.133003, -------------- Report Sync ------------
> Event: time 1287784361.145998, type 3 (Absolute), code 0 (X),
> value 14794
> Event: time 1287784361.146001, type 3 (Absolute), code 1 (Y),
> value 7221
> Event: time 1287784361.146010, type 3 (Absolute), code 3 (Rx),
> value 7221
> Event: time 1287784361.146014, -------------- Report Sync ------------
> Event: time 1287784361.158999, type 3 (Absolute), code 0 (X),
> value 14815
> Event: time 1287784361.159003, type 3 (Absolute), code 1 (Y),
> value 7284
> Event: time 1287784361.159010, type 3 (Absolute), code 2 (Z),
> value 15684
> Event: time 1287784361.159012, type 3 (Absolute), code 3 (Rx),
> value 7284
> Event: time 1287784361.159016, -------------- Report Sync ------------
> Event: time 1287784361.183994, type 4 (Misc), code 4 (ScanCode),
> value d0042
> Event: time 1287784361.183996, type 1 (Key), code 330 (Touch), value 0
> Event: time 1287784361.184014, -------------- Report Sync ------------
> ^C
>
> So you can see that the location of both fingers is reported for the
> multi-touch operation (with one finger reported as X & Y, and the
> second finger as Z & Rx). But with one finger, it's a bunch of button
> presses and then nearly instantaneous releases.
>
>
> And one final bit of information. Here is the relevant information from
> the udev.log:
> -----------------------------
> UDEV [1287664208.316717] add
> /devices/pci0000:00/0000:00:1d.2/usb8/8-2/8-2:1.0/input/input4/event4
> (input)
> UDEV_LOG=3
> ACTION=add
>
> DEVPATH=/devices/pci0000:00/0000:00:1d.2/usb8/8-2/8-2:1.0/input/input4/event4
> SUBSYSTEM=input
> DEVNAME=/dev/input/event4
> SEQNUM=1272
> ID_INPUT=1
> ID_INPUT_TABLET=1
> ID_VENDOR=Nexio_Touch_Device.
> ID_VENDOR_ENC=Nexio\x20Touch\x20Device.\x20\x20
> ID_VENDOR_ID=1870
> ID_MODEL=HID_Multi-Touch
> ID_MODEL_ENC=HID\x20Multi-Touch
> ID_MODEL_ID=0100
> ID_REVISION=0006
> ID_SERIAL=Nexio_Touch_Device._HID_Multi-Touch
> ID_TYPE=hid
> ID_BUS=usb
> ID_USB_INTERFACES=:030000:
> ID_USB_INTERFACE_NUM=00
> ID_USB_DRIVER=usbhid
> ID_PATH=pci-0000:00:1d.2-usb-0:2:1.0
> MAJOR=13
> MINOR=68
> DEVLINKS=/dev/char/13:68
> /dev/input/by-id/usb-Nexio_Touch_Device._HID_Multi-Touch-event-mouse
> /dev/input/by-path/pci-0000:00:1d.2-usb-0:2:1.0-event-mouse
>
> UDEV [1287664208.316759] add
> /devices/pci0000:00/0000:00:1d.2/usb8/8-2/8-2:1.0/input/input4/mouse1
> (input)
> UDEV_LOG=3
> ACTION=add
>
> DEVPATH=/devices/pci0000:00/0000:00:1d.2/usb8/8-2/8-2:1.0/input/input4/mouse1
> SUBSYSTEM=input
> DEVNAME=/dev/input/mouse1
> SEQNUM=1273
> ID_INPUT=1
> ID_INPUT_TABLET=1
> ID_VENDOR=Nexio_Touch_Device.
> ID_VENDOR_ENC=Nexio\x20Touch\x20Device.\x20\x20
> ID_VENDOR_ID=1870
> ID_MODEL=HID_Multi-Touch
> ID_MODEL_ENC=HID\x20Multi-Touch
> ID_MODEL_ID=0100
> ID_REVISION=0006
> ID_SERIAL=Nexio_Touch_Device._HID_Multi-Touch
> ID_TYPE=hid
> ID_BUS=usb
> ID_USB_INTERFACES=:030000:
> ID_USB_INTERFACE_NUM=00
> ID_USB_DRIVER=usbhid
> ID_PATH=pci-0000:00:1d.2-usb-0:2:1.0
> MAJOR=13
> MINOR=33
> DEVLINKS=/dev/char/13:33
> /dev/input/by-id/usb-Nexio_Touch_Device._HID_Multi-Touch-mouse
> /dev/input/by-path/pci-0000:00:1d.2-usb-0:2:1.0-mouse
> -----------------------------
>
> And if that isn't enough info, I'm happy to provide more.
>
>
> Thanks for whatever suggestions you can provide,
> Bill
>
> --
> Bill Sherman
> Sr. Technology Advisor
> Advanced Visualization Lab
> Pervasive Technology Inst
> Indiana University
>
shermanw@indiana.edu
> --
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