How to port Raspberry Pi's 7-inch touchscreen with Stm32mp157c-dk2?

[HArsl]

I have been trying to port touchscreen with Stm32mp157c-dk2 without success. Actually, touchscreen has 15 pins but Stm32 has 20 pins and I handled the unmatched pins on Stm in logical way. Rest of the pins match but no screen seen. Do I have to make adjustment in the SW side?

Best regards,

Halil

[AntonioST · Accepted solution]

I think the display you mention is this one

https://www.raspberrypi.org/products/raspberry-pi-touch-display/

I never used it, so the information below are not fully verified.

From HW side you need to connect several wires: GND, +3V3, +5V, I2C_SCL/SDA and the 6 wires for DSI CK,D0,D1 N and P.

Then you need to modify the device tree accordingly to

https://elixir.bootlin.com/linux/v4.19.9/source/Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchscreen.txt

and recompile the kernel adding the configuration option CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN

[HArsl]

Dear Antonio,

Thank you very much. I will try it and then give a feedback.

[HArsl]

Hi Antonio,

I have tried what you said me and resulted without success. I reconfigured the device tree accordingly the link and connected panel with connector just seen dark. I attached the device tree file below.

Best

Halil

[BSE]

Hi Halil,

I know your Question is a couple of months old but:

Have you solved the Problem and if so, how?

We've run into the same problem, but we solved the problem with the backlight Control:

You have to add these lines into the &i2c1 block:

&i2c1 {
      #address-cells = <1>;
      #size-cells = <0>;
 
lcd@45 {
        compatible = "raspberrypi,7inch-touchscreen-panel";
        reg = <0x45>;
        status="okay";
        port {
          panel_in: endpoint {
            remote-endpoint = <&dsi_out>;
          };
        };
};
[...SOME OTHER STUFF ...]
}

Comment out the Panel@0 block in &dsi to avoid compiling Errors due to the "dsi_out" port.

When the system boots up, the backlight of the display is activated - but there are just vertical lines and no proper screen output...

[ARicc.1]

Hi All,

any development on this topic? I'm interested too.

Thanks,

Aldo