From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki.Poulose@arm.com (Suzuki K Poulose) Date: Tue, 3 Jul 2018 10:44:13 +0100 Subject: [RFC PATCH 6/8] dts: coresight: Clean up the device tree graph bindings In-Reply-To: References: <1527858967-16047-1-git-send-email-suzuki.poulose@arm.com> <1527858967-16047-7-git-send-email-suzuki.poulose@arm.com> <20180612204802.GA15817@rob-hp-laptop> <5448BBB7-93FE-400F-9D87-FABF5DE0539C@arm.com> <075b99a1-2a29-f6dc-e9f2-99f895c27d35@arm.com> <5e013d65-9931-6b8d-ce7c-4333309d4ada@arm.com> Message-ID: <79d24815-278a-5465-65eb-afd3535236e7@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Rob, On 14/06/18 14:59, Rob Herring wrote: > On Thu, Jun 14, 2018 at 2:53 AM, Suzuki K Poulose > wrote: >> On 13/06/18 22:07, Matt Sealey wrote: >>> >>> >>> >>>> -----Original Message----- >>>> From: Mathieu Poirier >>>> >>>>> So, if the suggestion is to use an existing property "unit", I am fine >>>>> with it, if people agree to it. >>>> >>>> >>>> If we're going to have something sharply different than ACPI I prefer >>>> Rob's idea. >> >> >> No, the above comment is about using "unit" ( if it is a standard property >> for specifying something specific to hardware) instead of "coresight,hwid". >> I would prefer to stick to the DT graph bindings, because : > > "unit" is not a standard property and I don't like it either. > >> >> 1) The connections are bi-directional => Well, not necessarily >> bi-directional >> in terms of the data flow. But the connection information is critical. i.e, >> we need information about both the end-points of a connection, which the DT >> graph bindings solves. >> >> All we are missing is a way for specifying the "hardware port" number and >> the >> direction of flow. I don't see why do we need to create something new just >> for >> these two properties for something that exists today and works reasonably >> well >> for the usecase. > > If you have "in-ports" and "out-ports" nodes, then that gives you > direction and you can use reg for the "hardware port". > > in-ports { > port at 0 { > reg = <0>; > endpoint {...}; > }; > port at 1 { > reg = <1>; > endpoint {...}; > }; > }; > out-ports { > port at 0 { > reg = <0>; > endpoint {...}; > }; > }; > > I'll need to check, but dtc may need an update to not warn about this. > I did a quick check with the upstream dtc tool and the above form is doesn't generate any errors. Mathieu, Rob, Shall I proceed with the proposal above ? Suzuki