fix(t-deck): restore CALIBRATE_TOUCH so the touch panel is calibrated

[merocle]

Problem

The T-Deck touch panel is uncalibrated on the MUI build (t-deck-tft): a touch registers off by the 320/240 ratio — stretched by about 1.33 on X, compressed by about 0.8 on Y — accurate only near the bottom-left corner and worse with distance from it.

Cause

device-ui ships calibration parameters for this board and applies them in include/graphics/driver/LGFXDriver.h:

uint16_t parameters[8] = {0, 2, 0, 314, 223, 5, 224, 314};   // T_DECK
...
lgfx->setTouchCalibrate(parameters);

The whole block is behind #ifdef CALIBRATE_TOUCH. That flag was active for t-deck-tft until 8ae05f6 ("MUI: defcon tft display size definitions", #7142, 2025-06-26) commented it out while adding LGFX_SCREEN_WIDTH / LGFX_SCREEN_HEIGHT:

-  -D CALIBRATE_TOUCH=0
+;  -D CALIBRATE_TOUCH=0
+  -D LGFX_SCREEN_WIDTH=240
+  -D LGFX_SCREEN_HEIGHT=320

Neither that PR's description nor its discussion mentions touch, so this looks unintended. With the flag gone no calibration is applied at all and the panel runs on raw LovyanGFX values.

Fix

Uncomment the line. CALIBRATE_TOUCH=0 applies the stored parameters; =1 would run interactive calibration, which does not persist yet — there is a FIXME in device-ui about reading it back from storage.

Testing

Built t-deck-tft at v2.7.26.54e0d8d with this change and flashed app0 on a T-Deck Plus (868 MHz). Touch is accurate across the whole screen afterwards; before the change it missed as described above. LoRa, keyboard and trackball unaffected.

Not addressed here

t-deck is the only variant that sets CALIBRATE_TOUCH, so the calibration block in device-ui is currently dead code for every board, even though it also carries parameters for WT32_SC01, T_HMI, ESP32_2432S022, ESP32_2432S028RV1, UNPHONE, NODEMCU_32S and SENSECAP_INDICATOR. I do not have those boards, so this PR touches one line rather than all of them.

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • LilyGo T-Deck
  • LilyGo T-Beam
  • RAK WisBlock 4631
  • Seeed Studio T-1000E tracker card
  • Other

I have a T-Deck Plus and a Heltec V4 only. The change is scoped to the t-deck variant's build flags, so other boards cannot be affected.

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[github-actions]

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[NomDeTom]

Please retarget this change to develop

[mverch67]

Display calibration may be individual for each display, that's why there's a calibration function in Settings->Screen Calibration. Though I agree that some default values may be better than nothing, especially if the lovyanGFX default is so far off that the settings button cannot be reached.
Upon startup these default values are overwritten with the stored values (from the last screen calibration) in NodeDB.

[caveman99]

Please rebase this onto develop

[vidplace7]

Display calibration may be individual for each display, that's why there's a calibration function in Settings->Screen Calibration. Though I agree that some default values may be better than nothing, especially if the lovyanGFX default is so far off that the settings button cannot be reached. Upon startup these default values are overwritten with the stored values (from the last screen calibration) in NodeDB.

@mverch67 Alternatively. Can we prompt for screen calibration upon firstboot? (If a previous calibration is not already stored).

[mverch67]

@mverch67 Alternatively. Can we prompt for screen calibration upon firstboot? (If a previous calibration is not already stored).

that's also possible, yes. But there's already another prompt in place to set username / region. So we'd had two prompts (and for sure could think about having even more prompts), lol.

[caveman99]

@merocle last request to rebase this one liner onto develop, or i will do it myself and close this one.