On Tue, Jan 20, 2015 at 7:08 AM, Thomas Gleixner [off-list ref] wrote:

On Thu, 15 Jan 2015, Rob Herring wrote:

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On Thu, Jan 15, 2015 at 3:11 AM, Thomas Gleixner [off-list ref] wrote:

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On Wed, 14 Jan 2015, Rob Herring wrote:

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We do not change shared interrupts in any way. We provide an
alternative mechanism for braindead hardware. And if the at91 folks
are fine with the DT change, then it's their decision. Nothing forces
this on everyone.

We are changing how shared interrupts are described in DT. We don't
need 2 ways to describe them. We could say this is only for AT91 and
continue to describe shared interrupts as has been done forever. Then
the next platform that hits this problem will have to go thru the same
ABI breakage. Or we change DT practices to describe all shared
interrupts with a demux node. Given the way DTs are incrementally
created, it is not something we can check with review or tools, so we
will still have the same ABI breakage problem.

This is not describing the proper shared interrupts. This is a special
case for a special case of braindamaged hardware. Whats wrong with
doing that? We dont have to change that for all shared interrupts
because 99% of them have a proper hardware implementation and are not
affected by this.

What's wrong with serving the AT91 with a proper solution, which does
NOT inflict horrible hacks into the core code and does NOT weaken
sanity checks and does NOT require irq chip specific knowledge in
device drivers?

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There are probably ways to do this demux irqchip without a DT change.

So far you have not provided any useful hint how to do so.

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What's the problem with a DT change for a single platform, if the
maintainers are willing to take it and deal with the fallout?

What's the solution for a platform that an ABI break is not okay and
can't deal with the fallout?

There is no other platform affected. This is a break for a specific
set of devices and the 'fallout' is confined, well known and accepted.

So what's your problem, really?

Thanks,

        tglx