lkml.org 
[lkml]   [2015]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Generic DT binding for IPIs
From
Date
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



\
 
 \ /
  Last update: 2015-10-22 13:01    [W:0.072 / U:2.904 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site