[Buildroot] rpi-firmware package installs DTBs that are kernel version specific

[Buildroot] rpi-firmware package installs DTBs that are kernel version specific

[Floris Bos]

Hi,

Currently the rpi-firmware buildroot package downloads and installs 
binary DTB files.
Problem is that those DTB files seem to be kernel version specific, and 
the current ones only work properly with a rpi-3.18.y Linux kernel.
When you use them with a kernel build from the rpi-3.19.y or rpi-4.0.y 
branch mmc0 does not function.

Think it may be better if we remove the binary DTB file installation 
from the rpi-firmware package, forcing the user to compile the device 
tree files from kernel source instead, ensuring matching version.

Yours sincerely,

Floris Bos

[Buildroot] rpi-firmware package installs DTBs that are kernel version specific

[Frank Hunleth]

Hi Floris,

On Tue, Apr 28, 2015 at 11:15 AM, Floris Bos <bos@je-eigen-domein.nl> wrote:
>
> Hi,
>
> Currently the rpi-firmware buildroot package downloads and installs binary DTB files.
> Problem is that those DTB files seem to be kernel version specific, and the current ones only work properly with a rpi-3.18.y Linux kernel.
> When you use them with a kernel build from the rpi-3.19.y or rpi-4.0.y branch mmc0 does not function.

That makes sense. Thanks for posting why mmc0 doesn't function, since
I was seeing the same issue.

> Think it may be better if we remove the binary DTB file installation from the rpi-firmware package, forcing the user to compile the device tree files from kernel source instead, ensuring matching version.

I'm actually not sure of the benefit of the rpi-3.19.y or later
kernels due to the regular upstream rebasing of the repositories. It
sounds like this is yet another downside, and I'll send a patch
tomorrow to change the RPI2 to rpi-3.18.y barring new information or
someone beating me to it. That way the 2015.05 release will at least
work out of the box for the RPI2.

I'm with you on building the DTBs in principle. I never felt like I
was forced to use the DTBs that were copied to output/images by
rpi-firmware, but at a minimum, it would be nice if they weren't
copied over if you weren't using a compatible kernel.

Regards,
Frank

[Buildroot] rpi-firmware package installs DTBs that are kernel version specific

[Floris Bos]

Hi,

On 04/28/2015 09:12 PM, Frank Hunleth wrote:
> I'm actually not sure of the benefit of the rpi-3.19.y or later
> kernels due to the regular upstream rebasing of the repositories. It
> sounds like this is yet another downside, and I'll send a patch
> tomorrow to change the RPI2 to rpi-3.18.y barring new information or
> someone beating me to it. That way the 2015.05 release will at least
> work out of the box for the RPI2.

Yes, I think 3.18 is fine as default.
Although there may still be users that have a need for a later release, 
e.g. if they have a brand new USB device that is only properly supported 
in a later release.

> I'm with you on building the DTBs in principle. I never felt like I
> was forced to use the DTBs that were copied to output/images by
> rpi-firmware, but at a minimum, it would be nice if they weren't
> copied over if you weren't using a compatible kernel.

Technically the files are not copied over as the rpi-firmware dtb ends 
up in output/images/rpi-firmware and if you specify 
BR2_LINUX_KERNEL_INTREE_DTS_NAME="bcm2709-rpi-2-b" the kernel compiled 
one ends up in output/images
But it is still a bit confusing to have two dtbs under output/images
Might be cleaner to just reintroduce the -recently removed- 
BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS option, so at least copying the 
rpi-firmware ones can be disabled.


Yours sincerely,

Floris Bos