On 27/08/2024 11:22, Jan Kiszka wrote: > On 27.08.24 08:37, Krzysztof Kozlowski wrote: >> On Mon, Aug 26, 2024 at 11:50:04PM +0200, Jan Kiszka wrote: >>> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >>> >>> Describe also the VMAP registers which are needed in order to make use >>> of the PVU with this PCI host. Furthermore, permit to specify a >>> restricted DMA pool by phandle. >> >> That's an ABI break without explanation why it is necessary. >> > > It is needed in order to support the PVU, as written above. Above say only that you want a new feature and that's not really suitable explanation for ABI break, because answer to this is: add new feature without breaking existing users. But maybe there is a bug or something does not work or never work or there are no users, don't know. > > Previous versions of this binding likely didn't consider this use case > and therefore didn't describe all registers associated with the hardware. > > BTW, if you see a way to add the required registers without breaking > more than needed, I'm all ears. At least the kernel driver will continue > to work with older DTs when you disable PVU support or do not add a DMA > pool to the DT. If there is no ABI break, because driver still handles correctly old DTB, then mention it in the commit msg. Best regards, Krzysztof
