As of 3/22 the linux-fslc repo has been refreshed from downstream (kernel.org) to 5.4.28 but the support in imx-linux @ 5.4.3 for imx8mp is still missing.
We used to get imx-linux from freescale's git but now it is a separate development that is (somehow) upstream of linux-fslc?
Obviously we would prefer a vendor base repo but if imx8mp support is elsewhere...
imx-linux => linux-fslc => arm.linux.org.uk => kernel.org
imx-linux => arm.linux.org.uk => kernel.org
=> linux-fslc <= (ie., linux-fslc is a merge bucket and has no downstream at all)
If there is a document that states is Freescale's intention for linux-fslc wrt its up-stream (imx-linux) and down-stream (git.arm.linux.org?) and its intended refresh rate, it would be service to your customers.