From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH V5 18/30] dt-bindings: csky CPU Bindings Date: Fri, 28 Sep 2018 06:32:34 -0500 Message-ID: References: <62098e7d0a7fbdd09f44d7e23333dad258a01bd2.1537789737.git.ren_guo@c-sky.com> <20180927164317.GA8427@bogus> <20180928010312.GA4179@guoren-Inspiron-7460> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20180928010312.GA4179@guoren-Inspiron-7460> Sender: linux-kernel-owner@vger.kernel.org To: Guo Ren Cc: Andrew Morton , Arnd Bergmann , Daniel Lezcano , David Miller , Greg Kroah-Hartman , Jason Cooper , Marc Zyngier , Mark Rutland , Mauro Carvalho Chehab , Peter Zijlstra , Thomas Gleixner , "linux-kernel@vger.kernel.org" , "open list:GENERIC INCLUDE/ASM HEADER FILES" , devicetree@vger.kernel.org, Greentime Hu , Palmer Dabbelt List-Id: linux-arch.vger.kernel.org On Thu, Sep 27, 2018 at 8:03 PM Guo Ren wrote: > > On Thu, Sep 27, 2018 at 11:43:17AM -0500, Rob Herring wrote: > > On Tue, Sep 25, 2018 at 07:39:21AM +0800, Guo Ren wrote: > > > This patch adds the documentation to describe that how to add cpu nodes in > > > dts for SMP. > > > > > > Signed-off-by: Guo Ren > > > --- > > > Documentation/devicetree/bindings/csky/cpus.txt | 70 +++++++++++++++++++++++++ > > > 1 file changed, 70 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/csky/cpus.txt > > > > > > diff --git a/Documentation/devicetree/bindings/csky/cpus.txt b/Documentation/devicetree/bindings/csky/cpus.txt > > > new file mode 100644 > > > index 0000000..ee3901d > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/csky/cpus.txt > > > @@ -0,0 +1,70 @@ > > > +================== > > > +C-SKY CPU Bindings > > > +================== > > > + > > > +The device tree allows to describe the layout of CPUs in a system through > > > +the "cpus" node, which in turn contains a number of subnodes (ie "cpu") > > > +defining properties for every cpu. > > > + > > > +Only SMP system need to care about the cpus node and single processor > > > +needn't define cpus node at all. > > > > We've generally found this is not true. Even for single core, you can > > have power domains, clocks for DVFS, etc. > Ok, I'll remove it. > > > > > > + > > > +===================================== > > > +cpus and cpu node bindings definition > > > +===================================== > > > + > > > +- cpus node > > > + > > > + Description: Container of cpu nodes > > > + > > > + The node name must be "cpus". > > > + > > > + A cpus node must define the following properties: > > > + > > > + - #address-cells > > > + Usage: required > > > + Value type: > > > + Definition: must be set to 1 > > > + - #size-cells > > > + Usage: required > > > + Value type: > > > + Definition: must be set to 0 > > > + > > > +- cpu node > > > + > > > + Description: Describes one of SMP cores > > > + > > > + PROPERTIES > > > + > > > > You need a compatible property for cpu nodes. > Our cpu is defined in defconfig, not in dts. I could put a comatible > property in here, but it's no use in code. It doesn't matter as that could change. Most arches do run-time selection of cpus within a range of compatible cores. And read the DT spec (devicetree.org) which says compatible is required for cpu nodes. Rob From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:37616 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729330AbeI1R4H (ORCPT ); Fri, 28 Sep 2018 13:56:07 -0400 MIME-Version: 1.0 References: <62098e7d0a7fbdd09f44d7e23333dad258a01bd2.1537789737.git.ren_guo@c-sky.com> <20180927164317.GA8427@bogus> <20180928010312.GA4179@guoren-Inspiron-7460> In-Reply-To: <20180928010312.GA4179@guoren-Inspiron-7460> From: Rob Herring Date: Fri, 28 Sep 2018 06:32:34 -0500 Message-ID: Subject: Re: [PATCH V5 18/30] dt-bindings: csky CPU Bindings Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org List-ID: To: Guo Ren Cc: Andrew Morton , Arnd Bergmann , Daniel Lezcano , David Miller , Greg Kroah-Hartman , Jason Cooper , Marc Zyngier , Mark Rutland , Mauro Carvalho Chehab , Peter Zijlstra , Thomas Gleixner , "linux-kernel@vger.kernel.org" , "open list:GENERIC INCLUDE/ASM HEADER FILES" , devicetree@vger.kernel.org, Greentime Hu , Palmer Dabbelt Message-ID: <20180928113234.8TAOyu9jR8KedFxTJnAlPaOy5zF8rbGhsl1VumQIrrg@z> On Thu, Sep 27, 2018 at 8:03 PM Guo Ren wrote: > > On Thu, Sep 27, 2018 at 11:43:17AM -0500, Rob Herring wrote: > > On Tue, Sep 25, 2018 at 07:39:21AM +0800, Guo Ren wrote: > > > This patch adds the documentation to describe that how to add cpu nodes in > > > dts for SMP. > > > > > > Signed-off-by: Guo Ren > > > --- > > > Documentation/devicetree/bindings/csky/cpus.txt | 70 +++++++++++++++++++++++++ > > > 1 file changed, 70 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/csky/cpus.txt > > > > > > diff --git a/Documentation/devicetree/bindings/csky/cpus.txt b/Documentation/devicetree/bindings/csky/cpus.txt > > > new file mode 100644 > > > index 0000000..ee3901d > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/csky/cpus.txt > > > @@ -0,0 +1,70 @@ > > > +================== > > > +C-SKY CPU Bindings > > > +================== > > > + > > > +The device tree allows to describe the layout of CPUs in a system through > > > +the "cpus" node, which in turn contains a number of subnodes (ie "cpu") > > > +defining properties for every cpu. > > > + > > > +Only SMP system need to care about the cpus node and single processor > > > +needn't define cpus node at all. > > > > We've generally found this is not true. Even for single core, you can > > have power domains, clocks for DVFS, etc. > Ok, I'll remove it. > > > > > > + > > > +===================================== > > > +cpus and cpu node bindings definition > > > +===================================== > > > + > > > +- cpus node > > > + > > > + Description: Container of cpu nodes > > > + > > > + The node name must be "cpus". > > > + > > > + A cpus node must define the following properties: > > > + > > > + - #address-cells > > > + Usage: required > > > + Value type: > > > + Definition: must be set to 1 > > > + - #size-cells > > > + Usage: required > > > + Value type: > > > + Definition: must be set to 0 > > > + > > > +- cpu node > > > + > > > + Description: Describes one of SMP cores > > > + > > > + PROPERTIES > > > + > > > > You need a compatible property for cpu nodes. > Our cpu is defined in defconfig, not in dts. I could put a comatible > property in here, but it's no use in code. It doesn't matter as that could change. Most arches do run-time selection of cpus within a range of compatible cores. And read the DT spec (devicetree.org) which says compatible is required for cpu nodes. Rob