Hi, On Fri, Nov 10, 2023 at 1:04 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Thu, Nov 09, 2023 at 06:06:03PM +0800, Chen-Yu Tsai wrote: > > In cases where the same Chromebook model is manufactured with different > > components (MIPI DSI panels, MIPI CSI camera sensors, or trackpad / > > touchscreens with conflicting addresses), a different SKU ID is > > allocated to each specific combination. This SKU ID is exported by the > > bootloader into the device tree, and can be used to "discover" which > > combination is present on the current machine. Thus we no longer have > > to specify separate compatible strings for each of them. > > You just broke an existing kernel with a new DT having this change. > > Just because you come up with a new way to do things, doesn't mean you > can remove the old way. I was wondering about that, actually. My understanding was that what Chen-Yu was doing here was correct, but I'm happy to be educated. Specifically, I think that after his series old device trees will continue to boot just fine. ...so if someone took a device tree from before his series and booted it on a kernel after his series that everything would be hunky dory. If that doesn't work then, I agree, that should be fixed. However, here, he is documenting what the "latest and greatest" device tree should look at and that matches what's checked into the "dts" directory. In general, I thought that yaml files didn't necessarily always document old/deprecated ways of doing things and just focused on documenting the new/best way. Now, obviously, if someone took a new device tree and tried to put it on an old kernel then it wouldn't work, but I was always under the impression that wasn't a requirement. -Doug
