Ronbo panel broken after Yocto update

[oli1]

Hey guys,

We recently updated the Yocto version we use (from 4.9-rocko to 4.14-sumo) and now our display panel just shows a white screen. The driver we're using is identical and the relevant sections of the DTB are the same, the only reason we updated was to fix some issues we were having with the UUU tool. Are there any breaking changes in the drm/display subsystem I'm unaware of?

We're using the iMX8MQ-EVK board.

Kind regards

Oli

[igorpadykov]

Hi Oli

one can try to rebuild all image from scratch, use software from source.codeaurora.org/external/imx,

pay attention that uboot also should be changed v.2018.03 for L4.14:

uboot-imx - i.MX U-Boot 

Best regards
igor
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[oli1]

Hi Igor,

Thanks for the swift reply.

I can confirm that we are using u-boot v2018.03 and kernel 4.14.98. I also attempted a full clean build. This did not fix our issue.

Kind regards

Oli

[igorpadykov]

Hi Oli

L4.14 added filtering unsupported frequencies in "int valid_clocks[]"
nwl-dsi.c\bridge\drm\gpu\drivers - linux-imx - i.MX Linux kernel 
It wasn't mentioned in kernel 4.9.88:

nwl-dsi.c\bridge\drm\gpu\drivers - linux-imx - i.MX Linux kernel 

One can try workarounds provided on

https://community.nxp.com/thread/513899 

Best regards
igor