Hi, sorry for jumping in. On 20-10-02 10:20, Krzysztof Kozlowski wrote: > On Fri, Oct 02, 2020 at 09:41:28AM +0200, Ahmad Fatoum wrote: > > Hello, > > > > On 10/1/20 12:37 PM, Krzysztof Kozlowski wrote: > > >> The existing binding doesn't cover these boards then and needs to be > > >> extended, no? How about following patch? > > > > > > What do you mean it doesn't cover? It was added exactly to handle them: > > > + - technexion,imx6q-pico-dwarf # TechNexion i.MX6Q Pico-Dwarf > > > + - technexion,imx6q-pico-hobbit # TechNexion i.MX6Q Pico-Hobbit > > > + - technexion,imx6q-pico-nymph # TechNexion i.MX6Q Pico-Nymph > > > + - technexion,imx6q-pico-pi # TechNexion i.MX6Q Pico-Pi > > > > > > > Still they are unused. So I'd think these boards should be handled like boards > > that predated bindings: a binding is written that doesn't break existing users. > > OK, let's assume the binding is not correct and DTSes are good. > > > > > >> [I guess we need to keep the two-compatible list they were originally > > >> in for compatibility even if it's unused among upstream device trees?] > > > > > > You want to change both the binding (thus breaking the ABI) and update > > > the DTS to reflect new ABI. Then why having a binding at all? > > > > If we leave the old two-compatible enumeration intact, there is no ABI broken. > > Just to clarify, because I don't get here the "no ABI broken" part: > ABI is the binding, not the DTS. We can change intree DTS as we like, > replace compatibles, add nodes, remove nodes. There is no stability > requirement for DTS contents. > > If we leave two-compatible binding intact, it is a broken binding since > beginning. Removing non-working, fake ABI is not breaking it because it > could never work. The problem here is that it wasn't covered by the review and now we have the mess. I see the DTB and the Bootloader as Firmware. Now imagine if the bootloader for these boards had some dt-fixup logic which won't apply anymore or if the bootloader board init won't get called anymore since the bootloader folks used the compatible found in the DTS. This can cause a regression if the old Bootloader tries to boot the new Kernel+DTS. > > > I would assume that either binding is correct or DTS. You propose that > > > both are wrong and both need changes... in such case this is clearly > > > broken. > > > > IMO the DTS is the correct one. If you want to honor the author's intention > > that each base board has a different compatible, it should be an extra > > compatible and not replace the existing one that may be already in use. Question is what was the author's intention? @Fabio do you have any comments here? > OK, we can go with DTS approach. I fixed few of such cases as well, > assuming that DTS was intended and binding was incorrect. In such case > all boards will be documented under one compatible technexion,imx6q-pico > and DTS will not be changed. Or keep the exisiting bindings and adding the new one. Therefore the yaml needs to handle two cases for each imx6[qdl]: compatible = "technexion,imx6dl-pico-dwarf", "technexion,imx6dl-pico", "fsl,imx6dl"; and compatible = "technexion,imx6dl-pico", "fsl,imx6dl"; Regards, Marco
