Hi Andre, On Mon, 6 Dec 2021 at 18:01, Andre Przywara <[email protected]> wrote: > > On Mon, 6 Dec 2021 17:11:52 -0700 > Simon Glass <[email protected]> wrote: > > > Sync these files, obtained from Linux v5.15. > > Sorry, but this would be wrong. > How do you know which board it is? Highbank or Midway? We use the > same binary for both, and decide either by the DT nodes we find in DRAM > or by some autodetection (Cortex-A9 vs. Cortex-A15) if there are > differences. The memory size would possibly be wrong (it's a DIMM slot). > If you need *some* DT for build reasons, whatever, but at least go with > the empty stub. > > And I still don't get this whole development argument: Why would > anyone need some random or partial DT sample in the U-Boot tree to do > development? > If people develop a driver, the document to code against is the > *binding* documentation, which describes what to expect from the DT > nodes. Then you *test* it against an actual tree, but on the actual > hardware, in which case you get the actual DTB, from the board. > If a developer needs to take a sneak peek into an actual DTB, > there are so many simple ways to do that: QEMU's dumpdtb, RPi's SD > card content, U-Boot's "fdt addr $fdtcontroladdr; fdt print", the > kernel's /sys/firmware/devicetree/base, ... When you port U-Boot to a > board, getting hands on the actual DT is probably the least of your > problems. > > So why would we need some mostly wrong DTs in the U-Boot tree? > It seems to suggest that you can hack the DT to make things work, but > this sounds bonkers, as the real DTB comes from somewhere else (SPI > flash, SD card, generated based on command line), and patching U-Boot's > copy to make things work is just wishful thinking. > > I can see the hacker's desire to play around with the DTB from time > to time (What happens if the GPIO is wrong? Can we deal with two > instances of the same device?), but for those experiments there are > plenty of ways to achieve this - and be it temporarily replacing the > empty DT stub. I just feel that bending the (board's) DT design ideas > for a hacker's pleasure is not justified.
What, there are two boards? How was I supposed to know that? Where do the devicetree files come from? I was assuming it was Linux, but are they not even there? It doesn't really matter what the tree is, but I assume the base tree must come from *somewhere*. We want to sync that to U-Boot. Please add a doc/board/highbank.rts or similar. I think you have missed a lot of discussion about all this. Regards, Simon
