Re: [System-dt] Notes (brief) from System DT call: OpenAMP bindings

-----Original Message----- From: boot-architecture boot-architecture-bounces@lists.linaro.org On Behalf Of Stefano Stabellini Sent: mardi 1 septembre 2020 22:19 To: François Ozog francois.ozog@linaro.org Cc: boot-architecture@lists.linaro.org; system-dt@lists.openampproject.org; Tomas Evensen tomase@xilinx.com Subject: Re: [System-dt] Notes (brief) from System DT call: OpenAMP bindings

On Tue, 1 Sep 2020, François Ozog via System-dt wrote:

...

On Tue, 1 Sep 2020 at 14:49, Tomas Evensen tomase@xilinx.com wrote: Here are some brief notes from the meeting.

  If nothing else as a showcase on how much we miss Nathalie when she

is on vacation 😉

...

  Krzysztof Kepa – GE
  Mathieu Poirier – Linaro
  Etsam Anjum – Mentor
  Anrnoud Pouliquen – ST
  Loic Pallardy - ST
  Suman Anna - TI
  Dan Milea – Wind River
  Mark Dapoz – Wind River
  Tomas Evensen – Xilinx
  Stefano Stabellini – Xilinx
  Bruce Ashfield – Xilinx
  Ed Mooring – Xilinx
  Ben Levinsky - Xilinx

  Stefano went through slides.
  Overall idea:

    1.  Specify remoteproc channels with minimal information in System-DT

in a way that is as common as possible for all vendors.

...

  In particular, we are avoiding to have to specify the same memory

regions in more than one place. A resource group is specially

...

  marked to contain most information.
    2.  Use Lopper to create the vendor specific remoteproc specification
  Generating reserved-memory, etc. information that has duplicate

information.

...

  For the time being, no plans to unify the vendor specific information

that goes into the traditional device tree for Linux

...

    3.  Later (or in parallel), but without making it a gating item, start

discussions on what we can do to unify the vendor

...

  specific information in the traditional DT

  Discussion about how TI and ST might generate their specific information

from this specification.

...

  Stefano to send out examples and slides.
  Ben: Xilinx backend to Lopper is upstreamed and available as an

example. Might change as upstreaming continues.

...

  Question:
  * How do we configure VirtIO?

Could you describe more the VirtIO question so that relationship with

Linaro project Stratos is assessed?

I think this point refers to various vdev<x> buffers described under /reserved-memory which are linked from RemoteProc. From the Xilinx bindings:

reserved-memory {
#address-cells = <1>;
#size-cells = <1>;
ranges;

rpu0vdev0vring0: rpu0vdev0vring0@3ed40000 {
	compatible = "xilinx,openamp-ipc-1.0";
	no-map;
	reg = <0x3ed40000 0x4000>;
};
rpu0vdev0vring1: rpu0vdev0vring1@3ed44000 {
	compatible = "xilinx,openamp-ipc-1.0";
	no-map;
	reg = <0x3ed44000 0x4000>;
};
rpu0vdev0buffer: rpu0vdev0buffer@3ed48000 {
	compatible = "xilinx,openamp-ipc-1.0";
	no-map;
	reg = <0x3ed48000 0x100000>;
};
rproc_0_reserved: rproc@3ed000000 {
	compatible = "xilinx,openamp-ipc-1.0";
	no-map;
	reg = <0x3ed00000 0x40000>;
};

};

ST proposed an RFC to decouple virtio rpmsg device from rproc one. In this proposal, a DT node is introduced to described HW associated to virtio device (share memory, mboxes...) in order to make description generic between different SoCs. As Stephano is proposing a generic way to populate DT kernel rproc node from system DT, I propose to think about virtio rpmsg device node definition (and why not any virtio device) in a second step. Regards, Loic

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