On 20.08.2018 22:12, Rob Herring wrote: > On Sat, Aug 18, 2018 at 06:54:17PM +0300, Dmitry Osipenko wrote: >> Splitting GART and Memory Controller wasn't a good decision that was made >> back in the day. Given that the GART driver hasn't ever been used by >> anything in the kernel, we decided that it will be better to correct the >> mistakes of the past and merge two bindings into a single one. In a result > > As a result... > >> there is a DT ABI change for the Memory Controller that allows not to >> break newer kernels using older DT by introducing a new required property, >> the memory clock. Adding the new clock property also puts the tegra20-mc >> binding in line with the bindings of the later Tegra generations. > > I don't understand this part. It looks to me like you are breaking > compatibility. The driver failing to probe with an old DT is okay? Yes, DT compatibility is broken. New driver won't probe/load with the old DT, that's what we want. > OS's like OpenSUSE use new DTs with older kernel versions, so you should > consider how to not break them as well. I guess if all this is optional > or has been unused, then there shouldn't be a problem. That's interesting.. Memory Controller isn't optional, I guess we could change compatible to "nvidia,tegra20-mc-gart". Thierry, do you have any other suggestions?
