Am 28.04.2017 um 20:23 schrieb Michal Suchánek:
> On 2017-04-28 16:29, Andreas Färber wrote:
>> Am 27.04.2017 um 02:52 schrieb Tony Su:
>>> Thx for looking at this, and your analysis.
>>>
>>> AFAIK based on existing systemd functionality, I'm not sure that it's
>>> quite ready to extend hardware device support, my impression is that
>>> although on the Roadmap of what systemd wants to eventually do, today
>>> udev still primarily is the subsystem that detects and implements
>>> devices. I only know of systemd services mounting devices, but only
>>> after udev has done its work.
>>
>> I think you misunderstood: systemd is a way to execute userspace
>> commands on boot, as successor to, e.g., /etc/init.d/boot.local script.
>>
>> It is rumored to be possible to apply .dtbo files to /sys/firmware from
>> userspace; Raspbian has some dtmerge tool (never tried it myself).

Correction: dtoverlay seems the more relevant one - deals with Raspberry
Pi specific features such as DT parameters though.

>> You could either package a yourhat.service unit (that depends on
>> suitable other uniquely named services if applicable), or we could have
>> one service that iterates over an, e.g., /boot/dtboverlay.d/ directory
>> with 10-yourhat.dtbo, achieving ordering via filename prefix.
>>
>> Personally I see it as a more pressing issue to make sure there are
>> mainline drivers for the sensors etc. I run into, because that takes
>> more time, so I have not looked into writing/packaging such tools.
>> raspberrypi-userland is problematic, so we'd need a standalone package.
>> Any volunteers?
>>
>> Once we know what exactly we need to make it work technically, we can
>> start thinking about a new YaST module as equivalent to rpi-config.
>>
>> Note that as of this week Kernel:HEAD's dtb packages should be prepared
>> for overlays (i.e., node labels can be referenced by phandle now).
> 
> With that you can apply a few patches (or verify they are applied) and do
> 
> for i in /boot/dtboverlay.d/*.dtbo ; do cat $i >
> /sys/whatever/node/applies/overlays ; done
> 
> I had a branch with these somewhere so I can try dusting it off and see
> how many are still needed.

Hmm,

https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/overlays

is what I've come across? I.e. /sys/kernel/config/device-tree/overlays,
which is not yet in 4.11 (CONFIG_OF_CONFIGFS unavailable).

Being able to just write a .dtbo into configfs would of course be
easiest for us.

Regards,
Andreas

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