Matthias Brugger wrote:
On 10/03/2019 19:35, Per Jessen wrote:
Well, at least I have a vcio module that builds
now, we'll see it if
it also works.
It seems that there is another thread on this mailing list, but I
wasn't able to find it. What do you want to achieve?
nothing too complex I hope, I just want to control a series of WS2812
LEDs, using the code/utilities from
The code for
using the PWM to generate control signals for a line of
WS2812Bs also uses /dev/mem to access the Raspi hardware - with the
openSUSE kernel, this is blocked by CONFIG_STRICT_DEVMEM. I don't
any kernel argument or switch to disable that restriction. (I tried
strict_devmem=0, didn't work).
I'm rebuilding a kernel without CONFIG_STRICT_DEVMEM, but I can't
help wondering if we shouldn't have a dedicated kernel optimized for
use on the Raspi? Using kernel-default seems silly.
In general you can provide patches against openSUSE kernel
configuaration if there is anything you think it should be
Cool, I might well make some suggestions.
STRICT_DEVMEM is a security feature so IMHO there
should be a good
reason to disable it. From your email I understand that you want to
access PWM via /dev/mem. That looks wrong. The PWMs should be accessed
through the sysfs.
Yes, I get the idea of /dev/mem, but I see lots of code for Raspis that
is using /dev/mem ? None of what I have seen even mentions having to
Can you please give some more background on what you
want to do and
how you try to achieve that?
For controlling the WS2812, I need to transmit data at around 800kHz -
with libgpiod, I was only able to generate a waveform of about 400kHz
(on a gpio). I gave that up and then I stumbled on
which looks to be the right way to
That code expects to use /dev/vcio for talking to the GPU mailbox as
well as /dev/mem for working with the PWM.
Per Jessen, Zürich (5.3°C)
- dedicated server rental in Switzerland.
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