STM32MP135F-DK – Display corruption and system hang after GPIO keypad configuration

[pd18178]

Hi,

Greeting!

I am working on the STM32MP135F-DK board and trying to interface a 4x5 matrix keypad using GPIOs.

I configured the keypad as follows:

• Columns (C1–C5):

  • C1 → PE1 (Pin 37)

  • C2 → PF11 (Pin 35)

  • C3 → PF9 (Pin 33)

  • C4 → PD13 (Pin 31)

  • C5 → PE6 (Pin 29)

• Rows (R1–R4):

  • R1 → PA0 (Pin 40)

  • R2 → PA5 (Pin 38)

  • R3 → PA7 (Pin 36)

  • R4 → PE5 (Pin 32)

After modifying the device tree and flashing the updated .dtb, I observe the following issues:

1. The display becomes glitchy.

2. The boot logo appears corrupted.

3. The system becomes unresponsive after boot.

4. Recovery is only possible after reflashing the starter package using STM32CubeProgrammer.

From my analysis:

• Manual GPIO control seems to work correctly.

• The matrix_keypad driver is loaded not properly.

matrix_keypad 20480 0
matrix_keymap 12288 1 matrix_keypad

I suspect this might be related to incorrect GPIO or pinmux configuration, possibly causing a conflict with other peripherals (e.g., display).

Could you please help identify:

• The root cause of this issue?

• Whether these GPIOs conflict with LTDC or other peripherals?

• The correct way to configure GPIOs for a matrix keypad on this board?

Any guidance would be greatly appreciated.

Thank you!!

Regards,

Pragya 

[Erwan SZYMANSKI]

Hello @pd18178 ,
Could you please explain which modification did you make in the stm32mp135f-dk.dts Linux device tree ? Maybe you could copy or attach the DT.

You said "The matrix_keypad driver is loaded not properly". Is it a typo ? 

According to the default pin configuration of the STM32MP135F-DK board, I do not see anything pin conflict based on the default configuration.
As information, we can check dynamically in Linux the pin config through this debug command:

MP13 $> cat /sys/kernel/debug/pinctrl/soc:pinctrl@50002000/pinconf-pins

What do you mean by "The system become unresponsive after boot" ?

Kind regards,
Erwan.