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[tissot/ft5x06] Touchscreen unusable in Phosh: libinput reports "multiple touch down for same slot" — MT Type-B protocol violation from FT5x06 driver #250

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@Harish020904

Hi,

Running postmarketOS (systemd-edge, Phosh) on Xiaomi Mi A1 (tissot) using the generic qcom-msm8953 port.

The touchscreen is detected fine — kernel probes it, evdev gets events, coordinates look correct. But it's completely unusable in Phosh.

journalctl -b is full of:

kernel bug: driver sent multiple touch down for the same slot

Looking at evtest, the tracking ID sequence looks wrong. On every tap I see something like:

ABS_MT_TRACKING_ID = -1
ABS_MT_TRACKING_ID = 128
ABS_MT_POSITION_X = 500
ABS_MT_POSITION_Y = 2040
SYN_REPORT

ABS_MT_TRACKING_ID = -1
ABS_MT_TRACKING_ID = 129
...

It keeps incrementing the tracking ID without a clean slot transition, which is probably why libinput rejects it.

Device info:

  • Kernel: 7.0.9-msm8953 #1-postmarketos-qcom-msm8953
  • Input device: generic ft5x06 (38), event1
  • Properties: INPUT_PROP_DIRECT
  • Resolution: X 0..1079, Y 0..1919

I'm using the generic qcom-msm8953 target rather than a tissot-specific package, so I'm also not sure if the right DTB is being picked up at boot or if the touchscreen DT node is correct for this device.

Is this a known issue with the ft5x06 driver on this kernel, or is it more likely a DTB problem for tissot specifically?

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