Re: [PATCH RFC 2/3] hw/i2c: add mctp core

[Matt Johnston <matt@codeconstruct.com.au>]

On Fri, Nov 18, 2022 at 08:01:40AM +0100, Klaus Jensen wrote:
> On Nov 18 13:56, Jeremy Kerr wrote:
> > Hi Klaus,
> > 
> > > Add an abstract MCTP over I2C endpoint model. This implements MCTP
> > > control message handling as well as handling the actual I2C transport
> > > (packetization).
> > > 
> > With those changes, I can get control protocol going, and multi-packet
> > messages work. There's a couple of failures from unsupported commands,
> > but otherwise looks good:
> > 
> >   # mctp addr add 8 dev mctpi2c6
> >   # mctp link set mctpi2c6 up
> >   # mctp link set mctpi2c6 mtu 254
> >   # systemctl restart mctpd
> >   # busctl --no-pager call xyz.openbmc_project.MCTP \
> >     /xyz/openbmc_project/mctp au.com.CodeConstruct.MCTP \
> >     SetupEndpoint say mctpi2c6 1 0x1d

Hi Klaus,

Thanks for the MCTP model, it's useful here.

I needed the following patch to be able to call SetupEndpoint again when a
device has already been assigned an EID. That tries a Set Endpoint ID/
Get Endpoint ID, addressed to EID 0.

Cheers,
Matt

---
From cb7ad91474367f8e47bdaf03aba9a822f2648f41 Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@codeconstruct.com.au>
Date: Mon, 21 Nov 2022 15:10:13 +0800
Subject: [PATCH] i2c/mctp: Allow receiving messages to dest eid 0

The Null Destination ID, 0, is used for MCTP control messages when
addressing by physical ID. That is used for Get Endpoint ID and
Set Endpoint ID when querying/assigning an EID to an endpoint.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
---
 hw/i2c/mctp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/i2c/mctp.c b/hw/i2c/mctp.c
index 1775deb46f..9d9e519ba9 100644
--- a/hw/i2c/mctp.c
+++ b/hw/i2c/mctp.c
@@ -258,7 +258,8 @@ static int i2c_mctp_event_cb(I2CSlave *i2c, enum i2c_event event)
             goto drop;
         }
 
-        if (pkt->mctp.hdr.eid.dest != mctp->my_eid) {
+        if (!(pkt->mctp.hdr.eid.dest == mctp->my_eid
+            || pkt->mctp.hdr.eid.dest == 0)) {
             trace_i2c_mctp_drop_invalid_eid(pkt->mctp.hdr.eid.dest,
                                             mctp->my_eid);
             goto drop;
-- 
2.37.2