kernel 4.1 makes ti am335x touchscreen (common 4.3 inch 4D cape) unusable

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1

Hi,
I tested the latest jessie flasher image on my beaglebone black rev C and the anti-jitter algorithm that was probably swapped out in https://github.com/beagleboard/linux/commit/83edfdf30b6f8d0916e8283fb395589afb9bdacb is taking 100% CPU on my board (in the X process) and jitters like crazy until it completely freezes the UI. I’m back on 3.8 from 03-01-2015 and it’s fine. Perhaps I have a very noisy piece of hardware, but that would imply that I would see the same issue in 3.8. Maybe it’s the cape manager?

The thing that scares me is that I don’t even see tux during boot which would imply that it’s not the jitter-algorithm that’s at fault? Therefore I would like to do some kernel AB testing with/without the commit mentioned above.

I’ve never built my own kernel from source before but I’m willing to give it a shot to fix this pesky issue. What’s the best “hold your hand” resource for a first time kernel build from git clone to inserting the microsd into the BB?

Thanks,
Matt

2

Hi,
I tested the latest jessie flasher image on my beaglebone black rev C and the anti-jitter algorithm that was probably swapped out in https://github.com/beagleboard/linux/commit/83edfdf30b6f8d0916e8283fb395589afb9bdacb is taking 100% CPU on my board (in the X process) and jitters like crazy until it completely freezes the UI. I’m back on 3.8 from 03-01-2015 and it’s fine. Perhaps I have a very noisy piece of hardware, but that would imply that I would see the same issue in 3.8. Maybe it’s the cape manager?

Not very likely. If I had to guess I would say it is probably a “ported” driver that got reverted from one branch to the next. Also, I do recall this problem being discussed before on these groups, and I believe it was resolved. Possibly by the original poster. Passed that, I can not help much. But I have read that this can happen when the other ADC channels are enabled and in use when a touch screen is configured + enabled.

I’ve never built my own kernel from source before but I’m willing to give it a shot to fix this pesky issue. What’s the best “hold your hand” resource for a first time kernel build from git clone to inserting the microsd into the BB?

https://eewiki.net/display/linuxonarm/BeagleBone+Black