Re: [Buildroot] [PATCH v3 2/3] board/raspberrypi: allow non-matching globs for DTBs

[Fiona Klute via buildroot <buildroot@buildroot.org>]

Hi Niklas!

Am 10.02.25 um 13:47 schrieb Niklas Cassel:
> On Fri, Feb 07, 2025 at 06:14:57PM +0100, Fiona Klute via buildroot wrote:
>> From: "Fiona Klute (WIWA)" <fiona.klute@gmx.de>
>>
>> When installing DTBs from the rpi-firmware package
>> (BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS=y), there's no DTB directly in
>> the images directory because the kernel build doesn't provide one.
>
> Your new defconfig does not seem to have BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS
> set. What am I missing?

This change is independent of the defconfig, which is aimed at a board
that's well supported by in-tree DTS (both mainline and RPi downstream).
The only connection is that both are about support for RPi boards.

> Regardless, perhaps clarify/rephrase your commit message.

What needs clarifying in your opinion?

>> Using pre-compiled DTBs is discouraged, but useful for using mainline
>> kernels until suitable DTS can be merged, or to provide U-Boot with a
>> DTB (via the firmware bootloader) independent of whatever kernel DTB
>> is in use.
>
> I don't really understand which pre-compiled DTB you are using, since
> your series is not adding any DTB, and your defconfig does not have
> BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS set.
>
> However, wouldn't it be much better to rebase this series on either:
>
> 1) Romain's series:
> https://lore.kernel.org/buildroot/20250204163622.192932-3-romain.naour@smile.fr/
> which introduces BR2_LINUX_KERNEL_CUSTOM_DTS_PATH
>
> or
>
> 2) Your own series:
> https://lore.kernel.org/buildroot/20250207183455.1468220-1-fiona.klute@gmx.de/
>
>
> Then this series could provide a DT source file (.dts) instead of a binary
> blob (.dtb). Having a DTS file would make it easier for other buildroot
> contributors to make changes, and once upstream has a DTS merged, you can
> remove your DTS file provided by buildroot.

This patch has nothing to do with either series. Both of those series
aim to support building out-of-tree DTS and installing the resulting DTB.

This patch allows the post-image script to work if the user does not
have the kernel (or tools added by one of those series) build a DTB, and
instead sets BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS=y. If they have a
suitable DTS to build, there's no point in using that option. The
rpi-firmware package installs its pre-compiled DTBs into
"${BINARIES_DIR}"/rpi-firmware/, so the "${BINARIES_DIR}"/*.dtb glob
won't match anything, and including the literal glob in the FILES list
will lead to "file not found" errors.

In short: The purpose of this patch is only to make
BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS=y work without forcing the user to
adjust the post-image script.

Best regards,
Fiona

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