Colibri iMX8 RGB LCD Display using DC0 / Spread Spectrum

Dear Support,

we are currently trying to enable SSC (Spread Spectrum) for our RGB Display on iMX8.

I followed the guidances from below to enable the SSC via SCFW Porting Kit and could successfully build the SCU firmware. I could integrate it into Tezi Image and install it on the device (anyhow I cannot verify the the modified scu firmware is running).

Now from looking at the /sys/kernel/debug/clk/clk_summary I found that RGB clock is not derived from DC0_PLLx but from elcdif_pll (which is not affected by the SSC changes when I am right).

Is it possible to switch LCD clock to be derived from any of the modified PLLs? Can this be done via Device-Tree or also SCU-Firmware?


attached clk_summary output:

clk_summary.txt (33.6 KB)


did you check this one here?

Best Regards,

Matthias Gohlke

Hi @matthias.tx ,
Yes I already did. The main question is about the clock tree, not how to enable the Spread Spectrum.
I could build the new SCU firmware but don’t see any changes.
As far as I understood the SSC will only effect the DC0-PLLs but the RGB clock is not derived from these. That is the point where I want to change the clock tree.

Marco Behr

Hi Matthias,

could you have a look at this topic? Is it possible to route the clocks in such way?

Adding more information about the hardware / software configuration:
Colibri iMX8 QuadXPlus 2GB IT
custom carrier board - using 24bit RGB signals for display interface
Toradex BSP 5 (dunfell branch)