[Nexus 7 (2013) General] sfhub:
I don't think you read far enough in the logs (you'll notice they've already tried to improve many things people are complaining about in the past checkins, even before JWR66N)

3.Two Fingers Tapping Easy Connectivity.

4.co-axis problem with two finger.

2.[Issue 9323363] [FLO/DEB] [Touch] Scrolling not smooth

3.[Issue 9471817] [FLO/DEB] [Touch] Hover touches

1.Seeing lost touches.

2.Magic disappearing square.

3.Need to clean up small pointer dancing.

4.Pointer splitting.

5.Jumps between two large touches.

6.9521124:Poor performace in handwritten input method.

9366206: Device show multiple-ghost touch after connect HDMI and tilt device to 40~65 degree.

9471956: Unclean lift offs.

9471962: Edge swipes causing hooks or missing touch points.

2.Edge swipes lost (notification panel)

1.[Issue 8840158] [FLO] pinch zoom doesnt seem as responsive / reliable as on nakasi.

2.[Issue 8858019] [FLO] Poor touch resolution.

3.[Issue 9052815] [FLO] Dead "Bands" on the touch screen.

4.[Issue 8930391] Spurious touchscreen taps.

2.[8858019]Poor touch resolution.

3.[8840158]pinch zoom doesnt seem as responsive / reliable as on nakasi.

8717455: Holding touch panel edge by one finger,the touch action will be affected.

8768005: Holding Flo along the left edge of the device reveals false touch problems.

8840158: Pinch zoom in and out on chrome and maps doesnt seem as accurate / responsive as on nakasi.

8798827: Touch can not be correct clicked.

customer report: pin unlock will lose touch report.

1.Fix the Sensitivity Problem That Suspend and Wake up When Charging.

2.Modification for Algorithm, and Digital Parameters for ER Module.

a.Improve "double fat finger (22 phi copper)" performance when charging

a. Improve "double fat finger (22 phi copper)" performance.

b. Improve "fast drawing straight line" performance.

c. Improve "multi-finger in co-axis (8 phi copper)" performance.

d. Improve "under table lamp" performance.
​

Grounding to what? Physical ground? This is a battery operated device. It doesn't make sense to design it to connect to a physical ground.

Sure it needs to connect to the ground plane back to battery ground, but if it wasn't connected to your ground plane, your touch screen wouldn't work at all.

The most likely reason it is working when connecting a cable is the voltage/current characteristics are changing and placing your touches within the range the firmware is expecting and it probably uses different calibration when on USB/AC adapter mode.

Also you will notice in the kernel logs the elan driver will tell the firmware to behave differently based on whether it is connected to

Battery Mode

USB and AC Adapter Mode

SLIM Port to HDMI

It is quite possible the voltages and currents are different in each of these states and the firmware needs to adjust its parameters.

Clearly they can affect the multi-touch behavior in the firmware because they have fixed the multi-touch problem for some people but not others and introduced some new tap problems. If this was purely a "grounding" issue, by which you seem to mean the device isn't physically connected to ground properly, they wouldn't have been able to affect those behaviors at all in firmware, let alone fix some problems and add new ones.

It is also clear there are hardware variances at play here so it isn't purely a software issue.

I don't know if they will ultimately win at their game of whack-a-mole with the touchscreen issues, but clearly they can affect the behavior people are complaining about in firmware, so the possibility of it being fixed in firmware is there, but there is no guarantee they will end up fixing all or most of the issues without introducing new ones.