svn commit: r328257 - in head/sys: arm/broadcom/bcm2835 dts/arm modules

[Poul-Henning Kamp]

--------
In message <20180129132736.GA66330 at bluezbox.com>, Oleksandr Tymoshenko writes:

>> If I pick a RPI[23] out of the box, download a FreeBSD image,
>> put the card in and play around, I should be able to put a
>> LED in a breadboard and configure a line for PWM or attach
>> an I2C or SPI device without reboot between every single
>> experiment.
>
>No problem. We include pwm.dtbo in our snapshot and config.txt.
>We have PWM running out of the box. Problem solved, no need for
>any hacks. I'll gladly work with Glen and Brad to get this
>functionality in snapshots/builds.

You seem to have skipped the bit about "without reboot" ?

>Raspberry Pi and other hobbyist ARM boards are basically Lego.
>They can be turned into multiple things and that's their selling
>point. They're hackers' toys.

That's *exactly* why I want us to support them better.

>You ignored my question: what would be authoritative source for this
>kind of info? World is not perfect, FreeBSD/arm support is not perfect.
>We have limited resources. Where we should apply them to guide
>new contributors?

At the very least have some place to point developers for a
resonably up-to-date idea of what the FDT related architecture
in FreeBSD is.

Either documentation or source code (preferably with a bit of
contextual comments) on our chosen reference platform.  (Source
code on ref-platform is probably more robust, as there is a
better chance that it will be kept current.)

>You also ignored my question about clkman fix. Provided you have
>all the documentation you need [...]

I don't.  The information for the PWM case was based on an affine
transform of information for the GPIO clock some shrewed guesses
and finally in-lab measurement of what actually transpired when I
frobbed registers.

But more importantly, I have no idea what servies *a* clock
manager offers, through which apis and to what clients and
at what level of abstraction and flexibility ?

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.