Re: [PATCH] of: property: Add device link support for interrupts

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On 2021-01-20 09:53, Geert Uytterhoeven wrote:
Hi Saravana,

On Fri, Dec 18, 2020 at 10:11 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote:
Add support for creating device links out of interrupts property.

Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxxxx>
Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>

Thanks for your patch!

This does not seem to add all links.  I see links being created to the
secondary interrupt controller (e61c0000 "renesas,irqc"), but not to
the primary interrupt controller (GIC)

Which is good, as the GIC driver is not a platform_driver, and thus
creating links would break everything ;-)

BTW, I'd _love_ the GIC driver to be a platform_driver, as the GIC is
part of a power/and or clock domain on Renesas SoCs...

The trouble is that we need the GIC much earlier than the device model
is available, because the timer needs to be available super early.
This isn't specific to the GIC, by the way, but also to all root
interrupt controllers that end-up controlling the per-CPU interrupts.

If you try to relax this constraint, you'll end up observing some of the
very weird dependencies between sysfs, sched, and the device model (I went there a few years back, wasted a week on it, did a reset --hard on the branch,
and swore never to look at this again! ;-)

But for a start, I'd like the ITS code to be turned into a platform driver, as this would potentially allow for the various domains to be instantiated
dynamically. One day.

        M.
--
Jazz is not dead. It just smells funny...



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