Colibri iMX6ULL: Display timings on U-boot

Hi team,

A customer had an issue with the display timings of the custom LCD they are using, in which we could figure out the timings and make the appropriate device tree changes. Nothing too new.

However, even though that once the DTB is loaded with the kernel, displaying the image as expected, there are some issues just before that point that makes it not displaying correctly (which is more or less a couple of seconds) to which the customer is looking to make it look nicer.

My first thought was “Well, we need to add the display timings as well in the U-boot sources”. However, to my surprise, I didn’t find any on the device tree used on U-boot.

Comparing with the kernel sources, it seems that the whole lcdif pinux plus the display timings are simply not there (although the pinmux is on the board file instead), so this led me to a couple of questions:

  1. Is there any definition of any of our current displays in U-boot? I believe there must be something there (apart from the FB_MXC driver) that makes the image with our Logo correctly display, but I couldn’t find any display timing definition (it could be as simple as not looking in the correct place).

  2. Is adding the whole display definition (the same way like it is added in the kernel device tree), the way to go or is there any other way on adding custom display timings at U-boot?

Many thanks as always and regards,
Alvaro.

Hi Alvaro

Did you try to change the videomode variable in the U-Boot environment?
I expect this to work on Colibri iMX6ULL and Colibri iMX7.

Max

Hi Max, I did not, but that seems like the way to go :slight_smile: Many thanks!