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T
Tim_ho
Associate II
June 18, 2025
Solved

Enable LVDS panel on STM32MP257F-EV1 based on Android OS

  • June 18, 2025
  • 4 replies
  • 1081 views

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.

Best answer by PPAGE.13

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.

4 replies

PPAGE.13
PPAGE.13
ST Employee
June 18, 2025

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.
T
Tim_hoAuthor
Associate II
June 23, 2025

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.

 

 

T
Tim_hoAuthor
Associate II
June 24, 2025

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

 

PPAGE.13
PPAGE.13
ST Employee
June 25, 2025

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.
T
Tim_hoAuthor
Associate II
June 26, 2025

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.

PPAGE.13
PPAGE.13
ST Employee
June 30, 2025

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.
S
sanjaysb
Associate II
August 1, 2025

@PPAGE.13 

I'm new to embedded linux, but i need a 10" display, for Yocto based Linux setup,

Currently i have a 7" display the one which i got with EVK (stm32mp257f-ev1)

https://mjmwired.net/kernel/Documentation/devicetree/bindings/display/panel/panel-lvds.yaml

in this lvds_panel.yaml file i saw 

 

# Admatec 9904379 10.1" 1024x600 LVDS panel - admatec,9904379 - auo,b101ew05

# HannStar Display Corp. HSD101PWW2 10.1" WXGA (1280x800) LVDS panel - hannstar,hsd101pww2

 

So can i use these displays without modyfying any low level drivers or device tree.

Please at least give me a hint about selecting a display 

 

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