We've got a couple of SOM modules that often fail to enable the display when booting.
i.MX6 quad, Marshmallow based on android_M6.0.1_2.1.0
Looking at console log, I see the following errors:
mxc_sdc_fb fb@0: timeout when waiting for flip irq
mxc_sdc_fb fb@0: MXCFB_WAIT_FOR_VSYNC: timeout 0
The "MXCFB_WAIT_FOR_VSYNC" timeout occurs quite frequently, the "timeout when waiting for flip irq" happens much less frequently.
I've seen some posts about similar issues on the NXP site but they seem to be connected with having a splash screen dispayed by u-boot and keeping it displayed during the Android boot.
We are not displaying a splash-screen until the Android bootAnimation is activated.