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Moving the gpio from the regulator to the pwm-backlight node did the trick. Now there is no white flashing anymore.

Thank you very much for your support!

Moving the gpio from the regulator to the pwm-backlight node did the trick. Now there is no white flashing anymore.

Thank you very much for your support!

F&S Development Machine with Fedora 40 V1.1 (20.11.2025)

There is a new Virtual Machine with Fedora40 in your download section available
My F&S / Tools-Linux /VirtualMachines/Fedora40/64-bit (i.MX9)/ F_S_Development_Machine-Fedora_40_V1.1.ova

The structure…

Yes this is true.
The driver first enables the regulator then does the sleep and finally enables the enable-gpio.
https://github.com/FSEmbedded/…eo/backlight/pwm_bl.c#L57

You could try to add the property enable-gpio to the backlight node using the gpio…

With setting the delay to 20s I see first the white flicker and then black for 20s. I looked in the pwm-backlight code in pwm_bl.c. When I understood right the delay is setting the gpio defined in its devicetree node property enable-gpio (which is not…

Yes of cause, here the decompiled devicetree where I set the delay to 20s:

backlight_ldb {
compatible = "regulator-fixed";
regulator-name = "ldb-bl";
gpio = <0x12 0x08 0x00>;
regulator-min-microvolt = <0x325aa0>;
regulator-max-microvolt = <0x325aa0>;
…

Also, could you post a snippet of your lvds-panel and backlight device tree nodes?

Did you try a really long time span like 2000ms?
Just to make sure if its an timing issue or a driver sequence issue.

Your F&S Support Team

Thanks for your answer.

Meanwhile i found exactly the same and i tried i by setting post-pwm-on-delay-ms but i got still a white flashing while boot up. I would say it even get slightly longer...

Hello,

unblank_delay basically delayed the enable of the backlight by introducing a msleep at the end of the ipu init function.
https://github.com/FSEmbedded/…7dc798b5c3909c73a30e8f02f


You should get a similar functionality by adding the value …