On Monday, July 20, 2020, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
i *hope* that they implemented "unload dynamic dtb" by now.
Finally, if you need to remove all overlays in one-go, just call of_overlay_remove_all() which will remove every single one in the correct order.
it got implemented, thank goodness.
that means (hypothetically) that Cards can be powered from OTG, *unplugged live*, put into a *new housing* and not require a reboot.
ultimately some Cards might actually have small internal batteries or supercapacitors to keep running for long enough to transfer without external power.
cat tsys01.dtbo > /sys/kernel/config/device-tree/overlays/tsys01/dtbo
that looks pretty straightforward.
the rest is probably because the dragonboard was quite early, and now the docs are out of date
the rbpi doc looks pretty garbled. phandles. *that* was the name of the pointer thing i mentioned.
it doesn't help the person writing that document that the rbpi foundation actually changed the pinouts between versions of hardware, and of course everyone expects the old overlays to "just work".
this kind of hell is precisely why eoma68 will not be "upgraded". or if it is, it'll be "faster sdmmc" or "faster usb3" both of which do dynamic hardware-level runtime negotiation that has nothing to do with pinouts themselves.
i.e. there will *never* be "abandonment" of pinout definitions. a pin defined now as i2c-clk *will remain defined as such*, forever.
one minor complication with eoma68 is that all pins (except usb) are dual-purpose (GPIO) multiplexed however given that this is standard fare for shield headers i do not anticipate problems in the overlay fragment definitions.
l.