On Mon, May 05 2025, Tom Rini <tr...@konsulko.com> wrote: > On Mon, May 05, 2025 at 10:19:24PM +0200, Mark Kettenis wrote: >> > Date: Mon, 5 May 2025 07:48:43 -0600 >> > From: Tom Rini <tr...@konsulko.com> >> > >> > On Mon, May 05, 2025 at 11:45:05AM +0200, Rasmus Villemoes wrote: >> > > On Fri, May 02 2025, Tom Rini <tr...@konsulko.com> wrote: >> > > >> > > > On Fri, May 02, 2025 at 01:34:33PM +0200, Bruno Leite wrote: >> > > > >> > > >> From: Bruno Leite <br...@prevas.dk> >> > > >> >> > > >> >> > > >> Currently rpi5 uses a generic rpi_arm64_defconfig file that builds >> > > >> rpi4 >> > > >> devicetree. Add a defconfig that is specific to the rpi5 building the >> > > >> now available upstream dts for that board. The defconfig makes use of >> > > >> defconfig including that is now available and only changes the DTS >> > > >> related config. >> > > >> >> > > >> It is also necessary to add a more specific u-boot.dtsi to rpi5, since >> > > >> due to the ARCH_BCM283X config it will try to build the >> > > >> bcm283x-u-boot.dtsi and break. >> > > > >> > > > My question is, can we not adjust rpi_arm64_defconfig to be generic >> > > > enough and not have a problem on Pi 5 due to the default device tree? >> > > >> > > Not really. >> > > >> > > What we want is to have CONFIG_DEFAULT_DEVICE_TREE to point at the >> > > rpi5's .dts file, because we really want to build that and not some >> > > "random" dts file that doesn't have anything to do with the hardware. I >> > > know that kinda works for the setups where the .dtb built in U-Boot is >> > > not used for anything, but in our case, we really do want to use the >> > > .dtb from the U-Boot build - we inject various U-Boot specific stuff via >> > > the EXTRA_DTSI mechanism, e.g. public key for kernel verification. >> > > >> > > And due to CONFIG_SYS_SOC being bcm283x, and bcm283x-u-boot.dtsi >> > > referencing nodes that simply don't exist when building >> > > bcm2712-rpi-5-b.dts, the build breaks. >> > > >> > > Perhaps the real problem is CONFIG_SYS_SOC being bcm283x for rpi5? I >> > > don't really know why rpi4 is both bcm2711 and bcm2835 and what the >> > > difference is, but rpi5 only seems to include a bcm2712.dtsi which does >> > > not include further dtsi files. >> > > >> > > If rpi5 has nothing to do with bcm283x, then perhaps a better approach >> > > is to ensure that CONFIG_SYS_SOC is bcm2712 when building for >> > > rpi5. Something like adding a CONFIG_TARGET_RPI_5 choice and adding a >> > > 'default "bcm2712" if TARGET_RPI_5' ? >> > >> > OK, so I guess my next question is, is rpi_arm64 useful enough in the >> > end for Pi 3 and Pi 4? I would have expected that it doesn't matter what >> > tree we build in to U-Boot as we would be using the one passed to us by >> > the prior stage firmware, and then update that at run-time as needed. >> >> Works well enough for us on OpenBSD. And it would be nice if >> rpi_arm64 would work for the Pi 5 as well. > > But that gets back to my first question. Can we correct the code such > that we do whatever is required at run time, as the previous stage will > have assembled and passed a correct device tree already?
I think this is sort-of asking the wrong question. The problem is not about what dtb the prior stage hands us or what to do at run-time. [*] The problem is to have a defconfig that will compile bcm2712-rpi-5-b.dts, as part of the U-Boot build. As I said, it's quite likely that rpi5 isn't at all a part of the 'menu "Broadcom BCM283X family"', and it's the CONFIG_SYS_SOC="bcm283x" that prevents bcm2712-rpi-5-b.dts from being compiled (because the bcm283x-u-boot.dtsi doesn't apply to that .dts). Bruno's patches achieve that by adding a more-specific -u-boot.dtsi file (it doesn't seem that we need any of the bootph-all settings from the bcm283x.dtsi file), and adding a defconfig file that is based on arm64, but just changes the dt settings. Those who simply ignore what .dtbs are part of the U-Boot build and use blobs coming from elsewhere can probably use rpi_arm64_defconfig as-is for rpi5. Rasmus [*] That's mostly a solved packaging problem outside the scope of U-Boot itself: Just put whatever .dtb one wishes the prior stage to pass to U-Boot along with u-boot.bin in the FAT filesystem, and put kernel=u-boot.bin device_tree=u-boot.dtb in config.txt (sure, there might be drivers that need updating to take different compatibles or whatnot into account).
