[Buildroot] [PATCH] board/raspberrypi: use kernel Bluetooth mode

[Peter Seiderer <ps.report@gmx.net>]

Hello John,

On Wed, 14 Jul 2021 15:51:32 +0100, John Keeping <john@metanate.com> wrote:

> The default setting with miniuart-bt requires hciattach which is a
> deprecated utility in BlueZ.  Setting the krnbt parameter switches to
> the modern method of using serdev in the kernel removing the need for
> any userspace configuration to enable the Bluetooth controller.
>
> This is documented as applying to all Raspberry Pi variants so just
> enable it globally.
>
> Signed-off-by: John Keeping <john@metanate.com>
> ---
>  board/raspberrypi/post-image.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/board/raspberrypi/post-image.sh b/board/raspberrypi/post-image.sh
> index 9dbd98ef9b..a6728c686e 100755
> --- a/board/raspberrypi/post-image.sh
> +++ b/board/raspberrypi/post-image.sh
> @@ -16,7 +16,7 @@ do
>  			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
>
>  # fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
> -dtoverlay=miniuart-bt
> +dtoverlay=miniuart-bt,krnbt=on
>  __EOF__
>  		fi
>  		;;

I fully understand the aim of your patch, but it is beyond the the minimal
approach of the defconfigs (minimal as as starting point for own
enhancements - startup and at minimum serial console access if possible,
so even not all rpi defconfigs provide the DTB overlays) or as strong hint
your enhancement would not match the comment line above the changed line...

But for an alternative config.txt file handling (with better/easier support
for cutomizations) see [1]...

Regards,
Peter

[1] https://patchwork.ozlabs.org/project/buildroot/patch/20210321114002.31000-1-ps.report at gmx.net/