Re: [PATCH v8 09/10] dt-bindings: interconnect: Add interconnect-tags bindings

From: Saravana Kannan <saravanak@google.com>
To: Sibi Sankar <sibis@codeaurora.org>
Cc: Rob Herring <robh@kernel.org>,
	Georgi Djakov <georgi.djakov@linaro.org>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Matthias Kaehlcke <mka@chromium.org>,
	Rajendra Nayak <rnayak@codeaurora.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Jordan Crouse <jcrouse@codeaurora.org>,
	Evan Green <evgreen@chromium.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 09/10] dt-bindings: interconnect: Add interconnect-tags bindings
Date: Wed, 20 May 2020 12:13:27 -0700	[thread overview]
Message-ID: <CAGETcx9a=9pMonfyoNGqkkfaDwJ+=U6OqK1op5UYM2zQbktsXQ@mail.gmail.com> (raw)
In-Reply-To: <3a392629be195fa6bebca18309efffab@codeaurora.org>

On Wed, May 20, 2020 at 11:51 AM Sibi Sankar <sibis@codeaurora.org> wrote:
>
> On 2020-05-20 01:27, Saravana Kannan wrote:
> > On Tue, May 19, 2020 at 11:58 AM Rob Herring <robh@kernel.org> wrote:
> >>
> >> On Tue, May 12, 2020 at 03:53:26PM +0300, Georgi Djakov wrote:
> >> > From: Sibi Sankar <sibis@codeaurora.org>
> >> >
> >> > Add interconnect-tags bindings to enable passing of optional
> >> > tag information to the interconnect framework.
> >> >
> >> > Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
> >> > Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> >> > ---
> >> > v8:
> >> > * New patch, picked from here:
> >> >   https://lore.kernel.org/r/20200504202243.5476-10-sibis@codeaurora.org
> >> >
> >> >  .../devicetree/bindings/interconnect/interconnect.txt        | 5 +++++
> >> >  1 file changed, 5 insertions(+)
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/interconnect/interconnect.txt b/Documentation/devicetree/bindings/interconnect/interconnect.txt
> >> > index 6f5d23a605b7..c1a226a934e5 100644
> >> > --- a/Documentation/devicetree/bindings/interconnect/interconnect.txt
> >> > +++ b/Documentation/devicetree/bindings/interconnect/interconnect.txt
> >> > @@ -55,6 +55,11 @@ interconnect-names : List of interconnect path name strings sorted in the same
> >> >                        * dma-mem: Path from the device to the main memory of
> >> >                                   the system
> >> >
> >> > +interconnect-tags : List of interconnect path tags sorted in the same order as the
> >> > +                 interconnects property. Consumers can append a specific tag to
> >> > +                 the path and pass this information to the interconnect framework
> >> > +                 to do aggregation based on the attached tag.
> >>
> >> Why isn't this information in the 'interconnect' arg cells?
> >>
> >> We have 'interconnect-names' because strings don't mix with cells. An
> >> expanding list of 'interconnect-.*' is not a good pattern IMO.
>
> Rob,
> Currently the interconnect paths
> assume a default tag and only few
> icc paths require tags that differ
> from the default ones. Encoding the
> tags in the interconnect arg cells
> would force all paths to specify
> the tags. I guess that's okay.

I think that's the right thing. Those cells are meant to be "args" to
the provider.

> >
> > Also, is there an example for interconnect-tags that I missed? Is it a
> > list of strings, numbers, etc?
>
> Saravana,
> https://patchwork.kernel.org/patch/11527589/
> ^^ is an example of interconnect-tag useage.

If we actually merge interconnect-tags, I think the doc should be
updated. Instead of having to grep around.

-Saravana