Am 22. Februar 2025 21:13:56 MEZ schrieb Ayush Singh <ayush@xxxxxxxxxxxxxxx>: >Hello everyone. > >I have been looking at ways to do runtime devicetree overlay application, and was just wondering what the current status of the different proposals [0], [1] were. They seem to be quite old and I think they were already rejected, but due to all the broken links, I am not really sure about the exact reasons. Also, maybe we now have the solutions to some the blockers at the time. > > >Let me fist go over some of the use cases where I think dynamic devicetree overlays can be useful. I am mostly interested in their use in single board computers like PocketBeagle 2 [2], Raspberry Pi [3], etc. > > ># Uses > >## Dynamic Pin muxing > >A lot of SBC's aimed for creating hardware projects expose headers, where each pin can be used for multiple things like GPIO, I2C, PWM, etc, depending on the pinmux. I think Raspberry Pi has it's own solution to do userspace pinmux, but if userspace devicetree application was a thing, it could probably be used for this. Additionally, being able to use dynamic devicetree overlays for pin muxing would allow much easier transition to use proper device trees during production. > > >## Dynamic Sensors/Devices > >Using devices such as sensors, external ADCs, EEPROMs, etc are also a common usecase in SBC's. A lot of current solutions seem to be designed around using user-space drivers in such cases. This is a bit of a shame since Linux kernel already has drivers for a lot of these drivers, and they are probably going to be of higher quality than most user space drivers. > > ># Challenges > >## Security > >The concerns regarding security seemed to show up in the other proposals. There was a proposal to have a devicetree property to allow/deny the application of overlays in some nodes, with default being deny. Was it insufficient? > > >## Memory Leaks > >Currently, updating/removing properties leaks memory. Was it one of the reasons for the rejection of previous proposals? > > >Maybe kernel already has some solutions more suited to my usecase that I am unware of? > > >[0]: https://lore.kernel.org/all/1417605808-23327-1-git-send-email-pantelis.antoniou@xxxxxxxxxxxx/#t > >[1]: https://lore.kernel.org/all/20161220190455.25115-1-xypron.glpk@xxxxxx/ > >[2]: https://www.beagleboard.org/boards/pocketbeagle-2 > >[3]: https://www.raspberrypi.com/ > > >Best Regards, > >Ayush Singh > Hello Ayush, On [1] I gave up when I got the impression that the maintainers only wanted to further their own companies interest and did not show openness for a globally usable functionality. Best regards Heinrich
