On Tue, Sep 20, 2022 at 02:17:50PM +0200, Geert Uytterhoeven wrote: > Hi Conor, > > On Fri, Sep 16, 2022 at 12:40 AM Conor Dooley <mail@xxxxxxxxxxx> wrote: > > On 15/09/2022 23:26, Lad, Prabhakar wrote: > > > On Thu, Sep 15, 2022 at 10:36 PM <Conor.Dooley@xxxxxxxxxxxxx> wrote: > > >> On 15/09/2022 19:15, Prabhakar wrote: > > >>> riscv: boot: dts: r9a07g043: Add placeholder nodes > > >>> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > >>> Add empty placeholder nodes to RZ/Five (R9A07G043) SoC DTSI. > > >> Can you explain why do you need placeholder nodes for this and > > >> cannot just directly include the other dtsis? > > >> > > > Since the RZ/G2UL SoC is ARM64 where it has a GIC and on RZ/Five SoC > > > we have PLIC for interrupts. Also the interrupt numbering for RZ/Five > > > SoC differs from RZ/G2UL SoC hence we are not directly using the > > > RZ/G2UL SoC DTSI [0]. > > > > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/r9a07g043.dtsi?h=v6.0-rc5 > > > > > > For the RZ/Five SMARC EVK I am re-using the below files [1] (SoM) and > > > [2] (Carrier board) as the RZ/Five SMARC EVK is pin compatible. Since > > > I am re-using these when trying to compile the RZ/Five DTB I get > > > compilation errors since the nodes dont exist (and there is no way > > > currently we can delete the node reference when the actual node itself > > > isn't present) hence these place holders. > > > > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/rzg2ul-smarc-som.dtsi?h=v6.0-rc5 > > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/rzg2ul-smarc.dtsi?h=v6.0-rc5 > > > > If this method is acceptable to Geert, this explanation 100% needs to > > go into the commit message. > > We've been using these placeholders a lot in Renesas SoC-specific > .dtsi files, as they allow us to introduce gradually support for a new SoC > that is mounted on an existing PCB, and thus shares a board-specific > .dtsi file. Hence I'm fine with this. Aye, if you're happy with it then I am too... > > However, I think more properties can be dropped from the placeholders. > There is no need to have e.g. 'reg-names' and 'status = "disabled"' > (there is no compatible value, so no matching is done). ...and this makes a lot of sense. I'd still like a comment in the commit message though explaining why placeholder nodes are needed as opposed to just leaving it blank etc. Thanks, Conor.
