From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from service87.mimecast.com (service87.mimecast.com [91.220.42.44]) by ozlabs.org (Postfix) with ESMTP id 311B32C0205 for ; Wed, 14 Aug 2013 23:21:47 +1000 (EST) Message-ID: <520B8468.7050307@arm.com> Date: Wed, 14 Aug 2013 14:21:44 +0100 From: Sudeep KarkadaNagesha MIME-Version: 1.0 To: Benjamin Herrenschmidt Subject: Re: [GIT PULL] DT/core: cpu_ofnode updates for v3.12 References: <5208E2D3.7060005@arm.com> <3356439.a21MloFP7n@vostro.rjw.lan> <520A536C.3030600@arm.com> <520A7B00.8060405@arm.com> <1376428024.4255.14.camel@pasglop> <520B5584.7030608@arm.com> <1376480227.4255.66.camel@pasglop> In-Reply-To: <1376480227.4255.66.camel@pasglop> Content-Type: text/plain; charset=UTF-8 Cc: "devicetree@vger.kernel.org" , "linux-pm@vger.kernel.org" , Sudeep KarkadaNagesha , Viresh Kumar , "linux-kernel@vger.kernel.org" , "rob.herring@calxeda.com" , "Rafael J. Wysocki" , Olof Johansson , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 14/08/13 12:37, Benjamin Herrenschmidt wrote: > On Wed, 2013-08-14 at 11:01 +0100, Sudeep KarkadaNagesha wrote: >> Yes this doesn't cover the historical "ibm,ppc-interrupt-server#s", >> for >> which we can have PPC specific wrapper above the generic one i.e. get >> the cpu node and then parse for thread id under custom property. >=20 > A wrapper is wrong. I don't want to have to have all ppc callers to use > a different function. Ok. On the side note the main intention of this patch series[1] is to avoid calling of_get_cpu_node function once CPU devices are registered. It initialises the of_node in all the cpu devices using this function when registering the CPU device. It can be retrieved from cpu_dev->of_node. So direct users of of_get_cpu_node can be reduced to avoid unnecessary parsing of DT to find cpu node. >=20 > As I said, just make a generic one that returns a thread ID, ie, same > signature as the powerpc one. Make it weak, we can override it in > powerpc-land, IMO, making generic definition which adhere to the ePAPR specification as weak is not so clean. > or we can move the ibm,ppc-interrupt-server#s handling > into the generic one, it won't hurt, but leave the thread_id return > there, it doesn't hurt it will come in handy in a few cases without > causing code duplication. >=20 IMO moving of handling ibm,ppc-interrupt-server#s to generic code under #ifdef CONFIG_PPC seems to be cleaner approach than weak definitation. As per my understanding each thread is a different logical cpu. Each logical cpu is mapped to unique physical id(either present in reg field or legacy ibm,ppc-interrupt-server#s field). So given a logical cpu id we can get the cpu node corresponding to it. Looking @ smp_setup_cpu_maps in arch/powerpc/kernel/setup-common.c and the comment in the same file: "This implementation only supports power of 2 number of threads.." the thread id id is implicit in the logical cpu id. Do we need to fetch that from DT ? Regards, Sudeep [1] https://lkml.org/lkml/2013/7/22/219