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

Warner Losh imp at bsdimp.com
Mon Jan 29 06:54:08 UTC 2018


On Sun, Jan 28, 2018 at 11:39 PM, Oleksandr Tymoshenko <gonzo at bluezbox.com>
wrote:
>
> Ignoring value of ofw_bus_status_okay(dev) in probe method is
> wrong for number of reasons and pinctl and clocks were brought up
> as an example why "status" property is more than just
> attach/dont-attach flag. So there is strictly technical reason
> why it should be checked. Once this boilerplate code moves to
> simplebus bus probe method as I believe Warner proposed drivers
> will not be able to control this aspect any more.
>

I have patches that does exactly this. I have a few more that will allow
drivers some control over the situation planned, but they require hammering
out some things in newbus first, which I'll write up once I have something
workable and it's been blessed by a couple people I've asked to give
feedback. The writeup will just be the first round, not the final
destination, btw. We need to work out several tricky issues that are
interlocking to ensure that we can enable drivers selectively after boot
time. That's tricky for a lot of reasons, but the tl;dr version is that
embedded is different because you don't just enable a device, but all the
dependencies which, unlike x86, are often 'non-linear' and possibly
non-orthogonal to other devices (eg, you may either have A B and C enabled,
or D E and F, but never any other combination, how do you transition from
state to state sanely). It's a tricky ball of wax that we've neglected for
too long.

Warner


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