On Mon, Mar 18, 2024 at 09:48:06AM -0500, Rob Herring wrote: > On Mon, Mar 18, 2024 at 02:17:47PM +0100, Johan Hovold wrote: > > On Mon, Mar 18, 2024 at 03:00:40PM +0200, Dmitry Baryshkov wrote: > > > On Mon, 18 Mar 2024 at 13:09, Johan Hovold <johan+linaro@xxxxxxxxxx> wrote: > > > > The only device out there that should be affected by this is the WCN3991 > > > > used in some Chromebooks. To maintain backwards compatibility, mark the > > > > current compatible string as deprecated and add a new > > > > 'qcom,wcn3991-bt-bdaddr-le' for firmware which conforms with the > > > > binding. > > > > > This compatible doesn't describe new hardware kind. As such, I think, > > > the better way would be to continue using qcom,wcn3991-bt compatible > > > string + add some kind of qcom,bt-addr-le property. > > > > No, you can't handle backwards compatibility by *adding* a property. > > But you could add a property for the not broken case. That's a bit odd, > but so is your compatible. Sure, we could have a property that we only add for wcn3991-bt going forward. But we can't go back in time and add this property to all devicetrees and say that 'local-bd-address' is big endian unless that property is present (as that would leave all the non-wcn3991 devicetrees broken). > > I wanted to avoid doing this, but if we have to support Google's broken > > boot firmware for these devices, then this is how it needs to be done. > > Don't Chromebooks update everything together. So maybe we don't care in > this case? That was my hope, but Matthias seemed to suggest that we need to continue supporting the current (broken) binding because doing such a coordinated update may be easier said than done: https://lore.kernel.org/lkml/ZcuQ2qRX0zsLSVRL@xxxxxxxxxx/ A new compatible string (or one-off property) would allow them do make a change when they are ready (e.g. by only updating the devicetrees after all boot firmware has been patched and pushed out). Johan
