From: atish.patra@wdc.com (Atish Patra) To: linux-riscv@lists.infradead.org Subject: [RFC 1/2] dt-bindings: topology: Add RISC-V cpu topology. Date: Fri, 2 Nov 2018 13:34:06 -0700 [thread overview] Message-ID: <954ec7be-f7ba-4e00-70fe-130cb4b84e61@wdc.com> (raw) In-Reply-To: <CAL_Jsq+wProNynprMjQnrz1jmbZT9TmmA-_=vPUxCEED_8xONg@mail.gmail.com> On 11/2/18 6:09 AM, Rob Herring wrote: > On Thu, Nov 1, 2018 at 6:04 PM Atish Patra <atish.patra@wdc.com> wrote: >> >> Define a RISC-V cpu topology. This is based on cpu-map in ARM world. >> But it doesn't need a separate thread node for defining SMT systems. >> Multiple cpu phandle properties can be parsed to identify the sibling >> hardware threads. Moreover, we do not have cluster concept in RISC-V. >> So package is a better word choice than cluster for RISC-V. > > There was a proposal to add package info for ARM recently. Not sure > what happened to that, but we don't need 2 different ways. > > There's never going to be clusters for RISC-V? What prevents that? > Seems shortsighted to me. > Agreed. My intention was to keep it simple at first go. If package node is added, that would work for us as well. >> >> Signed-off-by: Atish Patra <atish.patra@wdc.com> >> --- >> .../devicetree/bindings/riscv/topology.txt | 154 +++++++++++++++++++++ >> 1 file changed, 154 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/riscv/topology.txt >> >> diff --git a/Documentation/devicetree/bindings/riscv/topology.txt b/Documentation/devicetree/bindings/riscv/topology.txt >> new file mode 100644 >> index 00000000..96039ed3 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/riscv/topology.txt >> @@ -0,0 +1,154 @@ >> +=========================================== >> +RISC-V cpu topology binding description >> +=========================================== >> + >> +=========================================== >> +1 - Introduction >> +=========================================== >> + >> +In a RISC-V system, the hierarchy of CPUs can be defined through following nodes that >> +are used to describe the layout of physical CPUs in the system: >> + >> +- packages >> +- core >> + >> +The cpu nodes (bindings defined in [1]) represent the devices that >> +correspond to physical CPUs and are to be mapped to the hierarchy levels. >> +Simultaneous multi-threading (SMT) systems can also represent their topology >> +by defining multiple cpu phandles inside core node. The details are explained >> +in paragraph 3. > > I don't see a reason to do this differently than ARM. That said, I > don't think the thread part is in use on ARM, so it could possibly be > changed. > >> + >> +The remainder of this document provides the topology bindings for ARM, based > > for ARM? > Sorry for the typo. >> +on the Devicetree Specification, available from: >> + >> +https://www.devicetree.org/specifications/ >> + >> +If not stated otherwise, whenever a reference to a cpu node phandle is made its >> +value must point to a cpu node compliant with the cpu node bindings as >> +documented in [1]. >> +A topology description containing phandles to cpu nodes that are not compliant >> +with bindings standardized in [1] is therefore considered invalid. >> + >> +This cpu topology binding description is mostly based on the topology defined >> +in ARM [2]. >> +=========================================== >> +2 - cpu-topology node > > cpu-map. Why change this? > To my ears, it felt a better name. But I don't mind dropping it in favor of cpu-map if we are going to standardize cpu-map for both ARM & RISC-V. > What I would like to see is the ARM topology binding reworked to be > common or some good reasons why it doesn't work for RISC-V as-is. > IMHO, ARM topology can be reworked and put it in a common place so that RISC-V can leverage that. My intention for this RFC patch was to start the ball rolling on cpu topology in RISC-V and see if DT approach is fine with everybody. I would be happy to see ARM code to move it to a common code base where RISC-V can reuse it. Regards, Atish > Rob >
WARNING: multiple messages have this Message-ID (diff)
From: Atish Patra <atish.patra@wdc.com> To: Rob Herring <robh+dt@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Damien Le Moal <Damien.LeMoal@wdc.com>, "alankao@andestech.com" <alankao@andestech.com>, Zong Li <zong@andestech.com>, Anup Patel <anup@brainfault.org>, Palmer Dabbelt <palmer@sifive.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Christoph Hellwig <hch@infradead.org>, "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>, Thomas Gleixner <tglx@linutronix.de> Subject: Re: [RFC 1/2] dt-bindings: topology: Add RISC-V cpu topology. Date: Fri, 2 Nov 2018 13:34:06 -0700 [thread overview] Message-ID: <954ec7be-f7ba-4e00-70fe-130cb4b84e61@wdc.com> (raw) Message-ID: <20181102203406.CcnMEqnWKHCuLiByeJtE9oow0skob22FT_9_JaCBreA@z> (raw) In-Reply-To: <CAL_Jsq+wProNynprMjQnrz1jmbZT9TmmA-_=vPUxCEED_8xONg@mail.gmail.com> On 11/2/18 6:09 AM, Rob Herring wrote: > On Thu, Nov 1, 2018 at 6:04 PM Atish Patra <atish.patra@wdc.com> wrote: >> >> Define a RISC-V cpu topology. This is based on cpu-map in ARM world. >> But it doesn't need a separate thread node for defining SMT systems. >> Multiple cpu phandle properties can be parsed to identify the sibling >> hardware threads. Moreover, we do not have cluster concept in RISC-V. >> So package is a better word choice than cluster for RISC-V. > > There was a proposal to add package info for ARM recently. Not sure > what happened to that, but we don't need 2 different ways. > > There's never going to be clusters for RISC-V? What prevents that? > Seems shortsighted to me. > Agreed. My intention was to keep it simple at first go. If package node is added, that would work for us as well. >> >> Signed-off-by: Atish Patra <atish.patra@wdc.com> >> --- >> .../devicetree/bindings/riscv/topology.txt | 154 +++++++++++++++++++++ >> 1 file changed, 154 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/riscv/topology.txt >> >> diff --git a/Documentation/devicetree/bindings/riscv/topology.txt b/Documentation/devicetree/bindings/riscv/topology.txt >> new file mode 100644 >> index 00000000..96039ed3 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/riscv/topology.txt >> @@ -0,0 +1,154 @@ >> +=========================================== >> +RISC-V cpu topology binding description >> +=========================================== >> + >> +=========================================== >> +1 - Introduction >> +=========================================== >> + >> +In a RISC-V system, the hierarchy of CPUs can be defined through following nodes that >> +are used to describe the layout of physical CPUs in the system: >> + >> +- packages >> +- core >> + >> +The cpu nodes (bindings defined in [1]) represent the devices that >> +correspond to physical CPUs and are to be mapped to the hierarchy levels. >> +Simultaneous multi-threading (SMT) systems can also represent their topology >> +by defining multiple cpu phandles inside core node. The details are explained >> +in paragraph 3. > > I don't see a reason to do this differently than ARM. That said, I > don't think the thread part is in use on ARM, so it could possibly be > changed. > >> + >> +The remainder of this document provides the topology bindings for ARM, based > > for ARM? > Sorry for the typo. >> +on the Devicetree Specification, available from: >> + >> +https://www.devicetree.org/specifications/ >> + >> +If not stated otherwise, whenever a reference to a cpu node phandle is made its >> +value must point to a cpu node compliant with the cpu node bindings as >> +documented in [1]. >> +A topology description containing phandles to cpu nodes that are not compliant >> +with bindings standardized in [1] is therefore considered invalid. >> + >> +This cpu topology binding description is mostly based on the topology defined >> +in ARM [2]. >> +=========================================== >> +2 - cpu-topology node > > cpu-map. Why change this? > To my ears, it felt a better name. But I don't mind dropping it in favor of cpu-map if we are going to standardize cpu-map for both ARM & RISC-V. > What I would like to see is the ARM topology binding reworked to be > common or some good reasons why it doesn't work for RISC-V as-is. > IMHO, ARM topology can be reworked and put it in a common place so that RISC-V can leverage that. My intention for this RFC patch was to start the ball rolling on cpu topology in RISC-V and see if DT approach is fine with everybody. I would be happy to see ARM code to move it to a common code base where RISC-V can reuse it. Regards, Atish > Rob > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2018-11-02 20:34 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-01 23:04 [RFC 0/2] Add RISC-V cpu topology Atish Patra 2018-11-01 23:04 ` Atish Patra 2018-11-01 23:04 ` [RFC 1/2] dt-bindings: topology: " Atish Patra 2018-11-01 23:04 ` Atish Patra 2018-11-02 13:09 ` Rob Herring 2018-11-02 13:09 ` Rob Herring 2018-11-02 13:31 ` Sudeep Holla 2018-11-02 13:31 ` Sudeep Holla 2018-11-02 15:11 ` Rob Herring 2018-11-02 15:11 ` Rob Herring 2018-11-02 15:50 ` Sudeep Holla 2018-11-02 15:50 ` Sudeep Holla 2018-11-02 20:53 ` Atish Patra 2018-11-02 20:53 ` Atish Patra 2018-11-02 21:08 ` Rob Herring 2018-11-02 21:08 ` Rob Herring 2018-11-02 20:34 ` Atish Patra [this message] 2018-11-02 20:34 ` Atish Patra 2018-11-05 19:38 ` Palmer Dabbelt 2018-11-05 19:38 ` Palmer Dabbelt 2018-11-05 20:10 ` Rob Herring 2018-11-05 20:10 ` Rob Herring 2018-11-06 0:12 ` Atish Patra 2018-11-06 0:12 ` Atish Patra 2018-11-06 10:03 ` Nick Kossifidis 2018-11-06 10:03 ` Nick Kossifidis 2018-11-06 11:37 ` Mark Rutland 2018-11-06 11:37 ` Mark Rutland 2018-11-01 23:04 ` [RFC 2/2] RISC-V: Introduce " Atish Patra 2018-11-01 23:04 ` Atish Patra 2018-11-02 18:58 ` [RFC 0/2] Add RISC-V " Nick Kossifidis 2018-11-02 18:58 ` Nick Kossifidis 2018-11-02 21:14 ` Atish Patra 2018-11-02 21:14 ` Atish Patra 2018-11-02 22:18 ` Nick Kossifidis 2018-11-02 22:18 ` Nick Kossifidis 2018-11-06 14:13 ` Sudeep Holla 2018-11-06 14:13 ` Sudeep Holla 2018-11-06 15:26 ` Nick Kossifidis 2018-11-06 15:26 ` Nick Kossifidis 2018-11-06 15:50 ` Sudeep Holla 2018-11-06 15:50 ` Sudeep Holla 2018-11-06 16:20 ` Mark Rutland 2018-11-06 16:20 ` Mark Rutland 2018-11-07 2:31 ` Nick Kossifidis 2018-11-07 2:31 ` Nick Kossifidis 2018-11-07 12:06 ` Mark Rutland 2018-11-07 12:06 ` Mark Rutland 2018-11-08 13:45 ` Nick Kossifidis 2018-11-08 13:45 ` Nick Kossifidis 2018-11-08 15:54 ` Mark Rutland 2018-11-08 15:54 ` Mark Rutland 2018-11-09 3:55 ` Nick Kossifidis 2018-11-09 3:55 ` Nick Kossifidis 2018-11-07 12:28 ` Sudeep Holla 2018-11-07 12:28 ` Sudeep Holla 2018-11-08 14:52 ` Nick Kossifidis 2018-11-08 14:52 ` Nick Kossifidis 2018-11-08 16:48 ` Sudeep Holla 2018-11-08 16:48 ` Sudeep Holla 2018-11-09 2:36 ` Nick Kossifidis 2018-11-09 2:36 ` Nick Kossifidis 2018-11-09 12:33 ` Sudeep Holla 2018-11-09 12:33 ` Sudeep Holla
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