Touchpad "DLL0662:00 06CB:2985" detected as a SynPS/2 Synaptics TouchPad an, making 3 / 4-finger gesture does not work after upgrade on 14.04.1

[Po-Hsu Lin]

CID: 201404-14997 Dell Vostro 3546

The touchpad was detected as "DLL0662:00 06CB:2985" on 14.04.1 stock image (3.13.0-32)
And it works with three / four finger tapping gesture.

But after upgraded to 3.13.0-48, it's detected as "SynPS/2 Synaptics TouchPad", therefore it can't do three / four finger tapping.
(bug 1384042)

ubuntu@201404-14997:~$ xinput list
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ SynPS/2 Synaptics TouchPad id=12 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
    ↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
    ↳ Power Button id=6 [slave keyboard (3)]
    ↳ Video Bus id=7 [slave keyboard (3)]
    ↳ Power Button id=8 [slave keyboard (3)]
    ↳ Sleep Button id=9 [slave keyboard (3)]
    ↳ Integrated_Webcam_HD id=10 [slave keyboard (3)]
    ↳ AT Translated Set 2 keyboard id=11 [slave keyboard (3)]
    ↳ Dell WMI hotkeys id=13 [slave keyboard (3)]

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-48-generic 3.13.0-48.80
ProcVersionSignature: Ubuntu 3.13.0-48.80-generic 3.13.11-ckt16
Uname: Linux 3.13.0-48-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.7
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: ubuntu 1415 F.... pulseaudio
 /dev/snd/controlC0: ubuntu 1415 F.... pulseaudio
CurrentDesktop: Unity
Date: Tue Mar 24 22:11:26 2015
HibernationDevice: RESUME=UUID=cb4a77a9-ee15-4ee5-b063-5c0b28a5d789
InstallationDate: Installed on 2015-03-24 (0 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Dell Inc. Vostro 3546
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-48-generic root=UUID=7d45912a-8768-4c39-8ec0-43eec97c733d ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-48-generic N/A
 linux-backports-modules-3.13.0-48-generic N/A
 linux-firmware 1.127.11
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: yes
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/05/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A04
dmi.board.name: 02R010
dmi.board.vendor: Dell Inc.
dmi.board.version: A04
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: Not Specified
dmi.modalias: dmi:bvnDellInc.:bvrA04:bd08/05/2014:svnDellInc.:pnVostro3546:pvrNotSpecified:rvnDellInc.:rn02R010:rvrA04:cvnDellInc.:ct8:cvrNotSpecified:
dmi.product.name: Vostro 3546
dmi.product.version: Not Specified
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Po-Hsu Lin (cypressyew)]

Compare the info from /proc/bus/input/device before and after upgrade, the 06cb:2985 device will be disappeared.

I: Bus=0018 Vendor=06cb Product=2985 Version=0100
N: Name="DLL0662:00 06CB:2985"
P: Phys=
S: Sysfs=/devices/pci0000:00/INT33C3:00/i2c-1/i2c-DLL0662:00/input/input7
U: Uniq=
H: Handlers=mouse0 event7
B: PROP=5
B: EV=b
B: KEY=e520 10000 0 0 0 0
B: ABS=673800001000003

[Po-Hsu Lin (cypressyew)]

On 14.04.3, it will still available, making 3/4-fingers gesture work.
Verified with 201408-15437 Dell Inspiron 3543