Re: how to enable spi on Raspberry Pi 4 (bookworm)?
On 10/25/22 12:03, Sebastian Kuzminsky wrote:
I'm using the 2022-08-08 bookworm rpi4 image from
<https://raspi.debian.net/tested-images/>, it's got linux-image-arm64
5.18.14-1 and raspi-firmware 1.20220331+ds-2.
It's working great, except I can't use the SPI devices.
SPI works on same hardware when running Raspbian's Buster image, after
running "dtparam spi=on" (or adding "dtparam=spi=on" to the firmware
config.txt file).
Raspbian Buster's dtparam program is not available on Debian Bookworm.
On Raspbian it comes from the libraspberrypi-bin deb, which is made from
the raspberrypi/firwmware git repo on github (the same repo that
supplies all the dtb files in /boot). dtparam and the other programs
there are provided in binary form (for armhf), not source :-(
I don't have this working yet but I've made a little bit of progress.
The Raspbian Buster armhf binaries can be made to run on Debian Bookworm
arm64 with a little bit of coaxing, but they rely on kernel features
that are not in Bookworm's arm64 kernel, so that's a bit of a dead end.
I then tried editing the dtb directly:
I "decompiled" the dtb `/boot/firmware/bcm2711-rpi-4-b.dtb` into an
editable dts with `dtc -I dtb -O dts $DTB > $DTS`.
I edited the dts to change the spi0 "status" field from "disabled" to "ok".
I "compiled" the edited dts with `dtc -I dts -O dtb $DTS > $DTB`.
I then replaced the old dtb with the new one and rebooted.
The spi port seems to be present/enabled now: dmesg includes
"spi-bcm2835 fe204000.spi: no tx-dma configuration found - not using dma
mode", and /sys/bus/platform/drivers/spi-bcm2835/fe204000.spi shows up.
But something is still wrong, there are still no /dev/spi* device files
like i get with Raspbian Buster.
So I'm closer, but I'm still missing something. The quest goes on!
--
Sebastian Kuzminsky
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