From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Linton Subject: Re: [PATCH v8 04/13] arm64/acpi: Create arch specific cpu to acpi id helper Date: Thu, 26 Apr 2018 13:33:14 -0500 Message-ID: References: <20180425233121.13270-1-jeremy.linton@arm.com> <20180425233121.13270-5-jeremy.linton@arm.com> <16324b54-42d4-d9bc-6d57-de52431dc209@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <16324b54-42d4-d9bc-6d57-de52431dc209@arm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Sudeep Holla , linux-acpi@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Lorenzo.Pieralisi@arm.com, hanjun.guo@linaro.org, rjw@rjwysocki.net, Will.Deacon@arm.com, Catalin.Marinas@arm.com, gregkh@linuxfoundation.org, Mark.Rutland@arm.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, wangxiongfeng2@huawei.com, vkilari@codeaurora.org, ahs3@redhat.com, Dietmar.Eggemann@arm.com, Morten.Rasmussen@arm.com, palmer@sifive.com, lenb@kernel.org, john.garry@huawei.com, austinwc@codeaurora.org, tnowicki@caviumnetworks.com, jhugo@qti.qualcomm.com, timur@qti.qualcomm.com, ard.biesheuvel@linaro.org List-Id: linux-acpi@vger.kernel.org Hi, On 04/26/2018 05:27 AM, Sudeep Holla wrote: > > > On 26/04/18 00:31, Jeremy Linton wrote: >> Its helpful to be able to lookup the acpi_processor_id associated >> with a logical cpu. Provide an arm64 helper to do this. >> > > As I pointed out in the earlier version, this patch is not required. > The acpi_id stored in the acpi_processor can be used for this. > Won't the below change make it work ? I can't think of any reason why it > shouldn't. So, I only noticed your previous email last night on the mail archive, as I was applying your review/ack tags and couldn't find a response for this patch, seem the spam/etc filters need some further tweaking! At that point, I was pretty sure the suggestion wasn't going to work out of the box as a lot of this code is running fairly early in the boot process. I spent a bit of time and plugged the change in to verify that assertion, and yes the per_cpu processor/acpi bits aren't setup early enough to be used by much of this code. It is being called from init_cpu_topology()/smp_prepare_cpus() which precedes do_basic_setup/do_initcalls() which is what runs the acpi_init() sequence which ends up eventually allocating the required data structures. So without restructuring the core boot sequence, this seems like a reasonable solution. Thanks, > > Regards, > Sudeep > > -->8 > > diff --git i/drivers/acpi/pptt.c w/drivers/acpi/pptt.c > index 0fc4b2654665..f421f58b4ae6 100644 > --- i/drivers/acpi/pptt.c > +++ w/drivers/acpi/pptt.c > @@ -432,7 +432,7 @@ static void cache_setup_acpi_cpu(struct > acpi_table_header *table, > { > struct acpi_pptt_cache *found_cache; > struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu); > - u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu); > + u32 acpi_cpu_id = per_cpu(processors, cpu)->acpi_id; > struct cacheinfo *this_leaf; > unsigned int index = 0; > struct acpi_pptt_processor *cpu_node = NULL; >