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

[Poul-Henning Kamp]

--------
In message <20180122145117.08173be547f5dd6fef296732 at bidouilliste.com>, Emmanuel
 Vadot writes:

> Using the same logic as before one could have a script starting some
>pwm stuff (or simply using /etc/sysctl.conf)
> Also this is not how DT is suppose to work, if the status ==
>'disabled' no driver should attach.

That doesn't make *any* UX sense.

"disabled" indicates that it can be enabled, and there is absolutely
no reason to force users to reboot, when all that stands between
them and using their hardware is a random setting in a file.

Explicitly kldload'ing a device-driver is as clear a "Enable it, please"
instruction as you can get from the user.

If you want to lock down this DT-device because some other
device/pin-mux/whatever makes its use impossible, then
status should not be "disabled" but "locked" or "impossible".

In particular it is *horrible* UX, that you kldload a device-driver
for hardware you know is there, and it just silently doesn't do
anything.  At the very least it should give a diagnostic.

Maybe something like:

	"For no good reason this device is disabled, google for
	an hour, try to come up with a device tree overlay, reboot
	to install it and see if you get lucky."

:-)

>> > Can you please revert this part ?
>> 
>> Once I find out how to get similar behaviour, ie: kldload without
>> having to reboot to load a DT-overlay.
>
> Nobody is working on that right now (that I know of).

Let me know when it works, and I'll remove my hack then.

In the meantime, don't load bcm283x_pwm if you don't plan on
using the PWM on GPIO12 on your RPI[23].

-- 
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.