Re: [PATCH v3 1/3] dt-bindings: i3c: xlnx: Add IBI and hot-join capability properties

From: Frank Li <Frank.li@oss.nxp.com>
To: Michal Simek <michal.simek@amd.com>
Cc: "Patil, Shubham Sanjay" <shubpati@amd.com>,
	Rob Herring <robh@kernel.org>,
	Shubham Patil <shubhamsanjay.patil@amd.com>,
	alexandre.belloni@bootlin.com, Frank.Li@kernel.org,
	krzk+dt@kernel.org, conor+dt@kernel.org,
	linux-i3c@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, git@amd.com
Subject: Re: [PATCH v3 1/3] dt-bindings: i3c: xlnx: Add IBI and hot-join capability properties
Date: Wed, 21 Oct 2026 10:13:17 -0500	[thread overview]
Message-ID: <atjWjd2sRy1P5HmR@SMW015318> (raw)
In-Reply-To: <c1c4d983-795d-4fba-84f5-7bd62246df02@amd.com>

On Wed, Oct 21, 2026 at 09:06:50AM +0200, Michal Simek wrote:
> Hi Rob,
>
> On 10/7/26 08:03, Patil, Shubham Sanjay wrote:
> > Hi Rob, Just a reminder !
>
> <snip>
>
> > > > > > > No reason to keep hj because the difference between HJ and IBI is the
> > > > > > > address when address arbitration. If hardware support IBI, it should support
> > > > > > > HJ. HJ just use special address 0x2.
> > > > > >
> > > > > > For this IP, they appear to be controlled by different configuration time
> > > > > > parameters, so I don't think conflating the two is the right thing to do
> > > > > > here:
> > > > > > https://docs.amd.com/r/en-US/pg439-axi-i3c/Configuration-Tab
> > > > > > Per this doc, and the original commit, hotjoin configuration is not
> > > > > > permitted when ibi is not supported but can be enabled and disabled
> > > > > > separately when it is.
> > > > >
> > > > > I am not sure why provide such flexiblity, only difference is that compare
> > > > > address 2 or other value.
> > > >
> > > > It's not unusual for FPGA IPs to provide extreme flexibility so that the
> > > > consumption of resources can be kept to a minimum, often to the point of
> > > > excessiveness. E.g. for a ethernet MAC IP each individual statistic might
> > > > have a configuration option.
> > > >
> > > > >
> > > > > This feature may be quite common for i3c, if other soft IP provider such
> > > > > flexiblity, still common property is the better than vendor specific one.
> > > >
> > > > I'm not at all in favour of speculatively adding properties for
> > > > configuration properties of FPGA IPs, particularly given the likelihood
> > > > of abuse by others. Without multiple demonstrated users, things shouldn't
> > > > be considered for being made common anyway.
> > >
> > > Rob:
> > >          What's your opinion? I predict we will met similar problem when
> > > I3C become popluar.
> > >          Do you perfer use vendor property fistly or direct add common
> > > property?
> > >          There will be back compatible problem if change vendor property to
> > > common property.
> > >
> > > Frank
>
> It looks like this thread is stuck and everybody is waiting for your opinion
> about it. Can you please take a look when you have time?

I suggest make a version, which support all enable/disable IBI/HJ. We can
discuss later. I think less possible to config two difference instance at
one SoC.

Frank

>
> Thanks,
> Michal
>