Enable LVDS panel on STM32MP257F-EV1 based on Android OS

Tim_ho · ‎2025-06-18

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.

PPAGE.13 · ‎2025-07-03

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.

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View solution in original post

PPAGE.13 · ‎2025-06-18

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

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Tim_ho · ‎2025-06-23

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 · ‎2025-06-24

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.

PPAGE.13 · ‎2025-06-25

Hi,

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

Philippe.

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Tim_ho · ‎2025-06-25

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.

Thanks.

PPAGE.13 · ‎2025-06-27

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.

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Tim_ho · ‎2025-06-27

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 · ‎2025-06-30

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.

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PPAGE.13 · ‎2025-06-30

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>;
};

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