<samueldr>
with my initial testing, it seemed to work
<samueldr>
(though in my case I was purposefully using the mainline kernel)
<pbb>
interesting
<pbb>
in addition to FDTDIR it sets FDT in the extlinux conf
<pbb>
I'll try that
<pbb>
with the rpi kernel the overlays are there and so on, just they don't get loaded. maybe that's the catch
<samueldr>
yes, with the generic distro thing in u-boot, when FDTDIR it _will_ load the FDT (dtb) from disk, and even fail booting if it can't find the one it expects
<samueldr>
I'm pretty sure that FDTDIR will not allow adding overlays, but haven't verified
<pbb>
"U-Boot only supports a DTB file, the kernel boots up fine, but the audio chip driver does not work."
<samueldr>
but likely that the generic distro concept (through extlinux.conf) cannot, not u-boot itself
<pbb>
ok
<pbb>
samueldr: it's working! \o/
<pbb>
I just manually applied the overlay for the hifiberry amp to the dtb files in /boot/nixos/*-dtbs/broadcom/
<pbb>
so the module is indeed what I want
<pbb>
it would be interesting to see if the overlay works with the mainline kernel
<samueldr>
when I was testing with the previously linked dtbocfg
<samueldr>
I found out that it might require fixes
<samueldr>
labels being different
<samueldr>
or something like that
<samueldr>
though not positive and once I have confirmation from someone else that "no, it just works" I'd take it on face value :)
<pbb>
doesn't seem like it
<pbb>
for the hifiberry-amp overlay fdtoverlay says "Failed to apply hifiberry-amp.dtbo (-1)"
<pbb>
when applying it to dtb files for mainline kernel
<pbb>
I guess using the full device tree from the raspberry pi kernel with the mainline kernel is less likely to work
<samueldr>
that's something I'd like to know, in theory device trees should... describe the device
<samueldr>
but in reality it seems to have been hijacked to also describe some runtime things :/
<samueldr>
like "which kernel driver to use"
<samueldr>
but not sure I'm right here in saying that
<pbb>
not so sure
<pbb>
the content of the dtbo file doesn't contain the name for the kernel module
<samueldr>
yeah, was going on a general tangent
<pbb>
the dtbo files are somehow compiled from dts files
<pbb>
wondering if that is specific to the kernel
<samueldr>
shouldn't be
<samueldr>
device trees are pretty universal, but I think they did originate from the kernel, not sure
<samueldr>
>> The device tree was derived from SPARC-based workstations and servers via the Open Firmware project. The current Devicetree specification[1] is targeted at smaller systems, but is still used with some server-class systems (for instance, those described by the Power Architecture Platform Reference).