Hi Peter, On Wed, 11 Dec 2024 at 09:36, Peter Robinson <[email protected]> wrote: > > > > On Mon, 9 Dec 2024 at 19:55, Simon Glass <[email protected]> wrote: >> >> The fdt_addr variable is used in extlinux as a fallback devicetree if >> none is provided by the boot command. > > > And what about where extlinux isn't used? > >> >> The existing mechanism uses the devicetree provided to U-Boot, but in >> its original, unrelocated position. For the rpi_4 I am using, this is >> at 2b35ef00 which is not a convenient place in memory, if the ramdisk >> is large. >> >> U-Boot already deals with this sort of problem by relocating the FDT >> to a safe address. >> >> So use the control-FDT address instead. > > > Please re-word the above, it doesn't make sense to me, "the rpi_4 I am using" > .... what about the other millions of RPis out there? > >> >> Remove the existing comment, which is confusing, since the FDT is not >> actually passed unmodified to the kernel: U-Boot adds various things >> using its FDT-fixup mechanism. > > > Don't remove it, re-word it so it's up to date. > >> >> Note that board_get_usable_ram_top() reduces the RAM top for boards with >> less RAM. This behaviour is left unchanged as there is no other >> mechanism for U-Boot to handle this. > > > The below looks irrelevant to the patch at hand, it looks like it should be > in the cover letter.
Do you have any comments on the code in this series? > >> >> In version 2, it incorporates some changes to fdt_addr, etc. suggested >> by Tom, as well as adding myself as a maintainer. >> >> Signed-off-by: Simon Glass <[email protected]> >> --- >> >> (no changes since v2) >> >> Changes in v2: >> - Drop patch to allow expanding the devicetree during relocation >> >> board/raspberrypi/rpi/rpi.c | 20 ++++++++------------ >> 1 file changed, 8 insertions(+), 12 deletions(-) >> >> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c >> index 9122f33d88d..8f6ab1b1b9b 100644 >> --- a/board/raspberrypi/rpi/rpi.c >> +++ b/board/raspberrypi/rpi/rpi.c >> @@ -3,6 +3,8 @@ >> * (C) Copyright 2012-2016 Stephen Warren >> */ >> >> +#define LOG_CATEGORY LOGC_BOARD >> + >> #include <config.h> >> #include <dm.h> >> #include <env.h> >> @@ -325,19 +327,10 @@ static void set_fdtfile(void) >> env_set("fdtfile", fdtfile); >> } >> >> -/* >> - * If the firmware provided a valid FDT at boot time, let's expose it in >> - * ${fdt_addr} so it may be passed unmodified to the kernel. >> - */ >> +/* Allow U-Boot to use its control FDT with extlinux if one is not provided >> */ >> static void set_fdt_addr(void) >> { >> - if (env_get("fdt_addr")) >> - return; >> - >> - if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC) >> - return; >> - >> - env_set_hex("fdt_addr", fw_dtb_pointer); >> + env_set_hex("fdt_addr", (ulong)gd->fdt_blob); >> } >> >> /* >> @@ -572,7 +565,10 @@ int ft_board_setup(void *blob, struct bd_info *bd) >> { >> int node; >> >> - update_fdt_from_fw(blob, (void *)fw_dtb_pointer); >> + if (blob == gd->fdt_blob) >> + log_debug("Same FDT: nothing to do\n"); >> + else >> + update_fdt_from_fw(blob, (void *)gd->fdt_blob); >> >> node = fdt_node_offset_by_compatible(blob, -1, "simple-framebuffer"); >> if (node < 0) >> -- >> 2.34.1 >> Regards, Simon
