Is there anything more I can do to get more attention about this? I
think Marc's suggestion is more generic and future proof, if I send RFC
patches for that would this be better?
Thanks,
Qais
On 10/14/2015 11:18 AM, Qais Yousef wrote:
Hi,
This is an attempt to revive a discussion on the right list this time
with all the correct people hopefully on CC.
While trying to upstream a driver, Thomas and Marc Zyngier pointed out
the need for a generic IPI support in the kernel to allow driver to
reserve and send ones. Hopefully my latest RFC patch will help to
clarify what's being done.
https://lkml.org/lkml/2015/10/13/227
We need a generic DT binding support to accompany that to allow a
driver to reserve an IPI using this new mechanism.
MarcZ had the following suggestion:
https://lkml.org/lkml/2015/8/24/628
Which in summary is
mydevice@f0000000 {
interrupt-source = <&intc INT_SPEC 2 &inttarg1 &inttarg1>;
};
inttarg1: mydevice@f1000000 {
interrupt-sink = <&intc HWAFFINITY1>;
};
inttarg2: cpu@1 {
interrupt-sink = <&intc HWAFFINITY2>;
};
interrupt-sink requests to reserve an IPI that it will receive at
HWAFFINITY cpumask. interrupt-source will not do any reservation. It
will simply connect an IPI reserved by interrupt-sink to the device
that will be responsible for generating that IPI. This description
should allow connecting any 2 devices.
Correct me Marc if I got it wrong please.
I suggested a simplification by assuming that IPIs will only be
between host OS and a coprocessor which would gives us this form which
I think is easier to deal with
coprocessor {
interrupt-source = <&intc INT_SPEC COP_HWAFFINITY>;
interrupt-sink = <&intc INT_SPEC CPU_HWAFFINITY>;
}
interrupt-source here reserves an IPI to be sent from host OS to
coprocessor at COP_HWAFFINITY. interrupt-sink will reserve an IPI to
be received by host OS at CPU_HWAFFINITY. Less generic but I don't
know how important it is for host OS to setup IPIs between 2 external
coprocessors and whether it should really be doing that.
What do the DT experts think? Any preference or a better suggestion?
I tried to keep this short and simple, please let me know if you need
more info or if there's anything that needs more clarification.
Thanks,
Qais
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