[U-Boot] FPGA detection failure on Cyclone V soc development kit

[Måns Rullgård]

I'm having a problem with u-boot 2016.01 failing to detect the FPGA on
my Altera Cyclone V SoC Development Kit.  On startup, it simply prints
"FPGA: Not Altera chip ID" (the ID having been read as all-zero).  No
amount of messing with jumpers or switches makes a difference.  The
software on the SD card included in the box appears to work, so on a
whim I took the SPL pre-loader from this card and combined it with the
main 2016.01 u-boot.  This makes the detection succeed, despite Marek
baulking at this idea.  The "good" SPL identifies as "U-Boot SPL
2013.01.01 (Dec 04 2014 - 08:59:41)" which is a different build date
than the main u-boot on the same SD card, so which source code version
it was built from is anyone's guess.

What's interesting is that Marek's board works with u-boot 2016.01 while
mine fails even with the very same binary.  The boards are different
revisions (his 100-0321003-C1, mine -E1), and the main Cyclone V chips
are also different (his 5CSXFC6D6F31C8NES, mine 5CSXFC6D6F31C6N).

Any suggestions for what to try next?

-- 
Måns Rullgård