On Mon, Oct 27, 2014 at 04:38:27PM +0530, Vignesh R wrote:

This series of patches fix TSC defects related to lag in touchscreen
performance and cursor jump at touch release. The lag was result of
udelay in TSC interrupt handler. Cursor jump due to false pen-up event.
The patches implement Advisory 1.0.31 in silicon errata of am335x-evm
to avoid false pen-up events and remove udelay.

That advisory has two workarounds. You have chosen the second one?

The text of the second workaround says it only works on 4 wire setups,
so I wonder how 5 wire designs will be affected.

The advisory says to use
steps 1 to 4 for ADC and 5 to 16 for TSC (assuming 4 wire TSC and 4 channel
ADC).

No, it doesn't say that. (sprz360f.pdf)

Further the X co-ordinate must be the last one to be sampled just
before charge step. The first two patches implement the required changes. 

FWIW, I implemented the first workaround and removed the udelay not
too long ago. Like Sebastian, I saw the TSC unit hang after about
50000 interrupts when running with the workaround.

Did you test you patch for very long?

Thanks,
Richard