Closed smoe closed 1 year ago
I recently played around with the Debian (not Raspberry PI OS, formerly known as Raspbian) bookworm aarch64 RPi4 image (2022-08-08) from https://raspi.debian.net/. It's built from https://salsa.debian.org/raspi-team/image-specs.
The good:
image-specs
build system was straightforward and easy to use and extend.irqaffinity=0-2 rcu_nocbs=3 rcu_nocb_poll isolcpus=domain,managed_irq,3 sysctl.kernel.sched_rt_runtime_us=-1
.The bad:
/sys/class/gpio/export
like one does in Raspberry Pi OS did not work. :-(I did some googleing and the entertaining blog entry https://waldorf.waveform.org.uk/2021/the-pins-they-are-a-changin.html pointed me to http://abyz.me.uk/lg/py_lgpio.html .
PCW has noted that you need to use ntpd rather than timesyncd https://forum.linuxcnc.org/38-general-linuxcnc-questions/46340-jittery-stepper-pulses-with-mesa-7i76e-solved?start=10#256153
https://waldorf.waveform.org.uk/2021/the-pins-they-are-a-changin.html
This points to gpiod, which is available in Debian and which does indeed let you twiddle the GPIO pins from userspace, so that's a good step forward.
But it doesn't help with the missing SPI - there's still no way to enable the SPI uart as far as i can see.
Please also follow that link to the lg library, this https://github.com/joan2937/lg I understand to be the github repository of it, which states to also be supporting SPI. I have not found it on Debian, but Ubuntu has it as https://launchpad.net/ubuntu/+source/lg-gpio .
I looked briefly at that and I think I just calls open()
on /dev/spidev
, which doesn't do the trick.
The problem is that /dev/spidev*
only exists if the device-tree says it should exist, and the dts in the kernel.org kernel says it should not exist. The raspbian kernel has extensive changes and additions to the dts, and changes to the kernel itself to allow loading dtb overlays at runtime, to do things like enable the SPI uarts.
This issue can be closed because we have a seperate repo for the Raspberry pi that addressses all of the concerns mentioned. Ref: https://github.com/LinuxCNC/rpi-img-builder-lcnc
Recommend this issue be closed
I just thought I bring this up to collect what comes to mind.
Other bits and pieces?