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Enable LVDS panel on STM32MP257F-EV1 based on Android OS

Tim_ho
Associate III

Dear ST Developer Support,

I want to enable LVDS panel on STM32MP257F-EV1 based on Android OS.

I tried to modify device tree stm32mp257f-ev1.dts and stm32mp257f-ev1-overlay.dts to enable LVDS panel.

But I could not enable it. When I revert the device fdt file, I saw that the LVDS related device tree nodes 

  • lvds

  • ltdc
  • panel-lvds

  • panel-lvds-backlight

  • display-controller

status were "disabled".

In stm32mp257f-ev1.dts and stm32mp257f-ev1-overlay.dts file, the LVDS related device note are status="okay".

So, I confuse on this problem. Maybe somewhere dts overlay this device node, but I cannot find it.

Would you help me solve this problem?

Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions

Hi,

to modify uboot/bootloader, you need to follow this documentation:

https://wiki.st.com/stm32mpu/wiki/How_to_build_bootloaders_for_Android

 

And in order to use another LVDS screen than the standard one (etml0700z9ndha) delivered with Eval board, you have comment the following section in 

"./device/stm/stm32mp2-bootloader/u-boot-stm32mp2/board/st/stm32mp2/stm32mp2.c" file (line 784)

 

      //if (board_is_stm32mp257_eval()) {
      // ret = fixup_stm32mp257_eval_panel(blob);
      // if (ret)
      //  log_err("Error during panel fixup ! (%d)\n", ret);
     //}

 

This will avoid to disable the DT node when another LVDS screen is used.

 

As explained in documentation, rebuild bootloader (build_bootloader), update it (build_bootloader -i), build full image (make -j) and reflash (flash-device).

Let me know if you have trouble,

BR,

Philippe.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

View solution in original post

15 REPLIES 15
PPAGE.13
ST Employee

Hi,

by default the LVDS panel is activated in our Android Package, you don't have to modify the device tree (stm32mp257f-ev1-overlay.dts)

If you don't have any display on LVDS screen , please check again documentation ( connection ?, ...)

https://wiki.st.com/stm32mpu/wiki/STM32MP25_Evaluation_boards_-_Starter_Package_for_Android

BR,
Philippe

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

Hi Philippe,

If I want to enable other LVDS panel on STM32MP257F-EV1 based on Android, I need to modify the device tree to meet my panel-timing. But I found the problem is that I set the LVDS related device tree node to status="okay". The LVDS still cannot enable. Would you have any idea?

Thanks.

 

 

Tim_ho
Associate III

Hi Philippe,

I use st-android-13.0.0-2024-07-31-stm32mp257f-ev1-emmc-starter to flash device. But I check lvds related node in device, I cannot see lvds node and device-tree status is disabled.

Would you help me resolve this problem?

Thanks.

Tim_ho_1-1750754254261.png

Tim_ho_2-1750754396491.png

 

Hi,

could you please check your dmesg output when driver is loaded?
thanks,

Philippe.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

Hi Philippe,

I have checked dmesg log, I cannot see any message about lvds driver.

But I check my .config, the lvds driver has built in.

Tim_ho_0-1750901120500.png

Thanks.

Hi Tim,

is the issue fixed on your side or you still face problem managing the dt. I am ot sure of the status of your last message.

BR,

Philippe.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

Hi Philippe,

This issue is still exist. I means that I cannot see any about lvds driver log on dmesg output when driver is loaded.

PPAGE.13
ST Employee

Hi,

could you please list the modifications you did on DT "stm32mp257f-ev1-overlay.dts" file (and other files ?) to adapt the setup for your specific LVDS screen?

And what is the new LVDS screen model?

BR,

Philippe.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.

You will have to adapt the following parameters to fit with your LVDS screen specification:

 

  panel-timing {
  clock-frequency = <54000000>;
  hactive = <1024>;
  vactive = <600>;
  hfront-porch = <150>;
  hback-porch = <150>;
  hsync-len = <21>;
  vfront-porch = <24>;
  vback-porch = <24>;
  vsync-len = <21>;
 };

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.