On Fri, 8 Nov 2024 11:24:36 -0600 Rob Herring <robh@xxxxxxxxxx> wrote: > On Fri, Nov 8, 2024 at 10:29 AM Herve Codina <herve.codina@xxxxxxxxxxx> wrote: > > > > Hi Rob, > > > > On Fri, 8 Nov 2024 10:03:31 -0600 > > Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > On Fri, Nov 8, 2024 at 8:36 AM Herve Codina <herve.codina@xxxxxxxxxxx> wrote: > > > > > > > > On systems where ACPI is enabled or when a device-tree is not passed to > > > > the kernel by the bootloader, a device-tree root empty node is created. > > > > This device-tree root empty node doesn't have the #address-cells and the > > > > > + /* > > > > + * #address-cells/#size-cells are required properties at root node > > > > + * according to the devicetree specification. Use same values as default > > > > + * values mentioned for #address-cells/#size-cells properties. > > > > > > Which default? We have multiple... > > > > I will reword: > > Use values mentioned in the devicetree specification as default values > > for #address-cells and #size-cells properties > > My point was that "default" is meaningless because there are multiple > sources of what's default. I see thanks. I will update the code comment. > > > > > > > There's also dtc's idea of default which IIRC is 2 and 1 like OpenFirmware. > > > > I can re-add this part in the commit log: > > The device tree compiler already uses 2 as default value for address cells > > and 1 for size cells. The powerpc PROM code also use 2 as default value > > for #address-cells and 1 for #size-cells. Modern implementation should > > have the #address-cells and the #size-cells properties set and should > > not rely on default values. > > > > In your opinion, does it make sense? > > > > > > > > > + */ > > > > + #address-cells = <0x02>; > > > > + #size-cells = <0x01>; > > > > > > I think we should just do 2 cells for size. > > > > Why using 2 for #size-cells? > > > > I understand that allows to have size defined on 64bits but is that needed? > > How to justify this value here? > > Most systems are 64-bit today. And *all* ACPI based systems are. Not > that the DT has to match 32 vs 64 bit CPU, most of the time it does. > > It also doesn't actually change anything for you because you're going > to have "pci" nodes and the "ranges" there takes #size-cells from the > pci node, not the parent. > Right. I will set: #address-cells = <0x02>; #size-cells = <0x02>; Best regards, Hervé
