Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932190AbbDNVtU (ORCPT ); Tue, 14 Apr 2015 17:49:20 -0400 Received: from mail-qk0-f181.google.com ([209.85.220.181]:33734 "EHLO mail-qk0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755177AbbDNVsu convert rfc822-to-8bit (ORCPT ); Tue, 14 Apr 2015 17:48:50 -0400 MIME-Version: 1.0 In-Reply-To: <20150414211720.GA56647@MBP> References: <1428601031-5366-1-git-send-email-galak@codeaurora.org> <20150410100529.GA6854@e104818-lin.cambridge.arm.com> <20150414163613.GM28709@leverpostej> <07185B2C-3F37-4E70-9096-1EF5EA8D68CE@codeaurora.org> <20150414211720.GA56647@MBP> Date: Tue, 14 Apr 2015 17:48:48 -0400 Message-ID: Subject: Re: [RFC PATCH 0/5] Add smp booting support for Qualcomm ARMv8 SoCs From: Rob Clark To: Catalin Marinas Cc: Kumar Gala , Mark Rutland , "devicetree@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , Will Deacon , "linux-kernel@vger.kernel.org" , "arm@kernel.org" , "abhimany@codeaurora.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3789 Lines: 83 On Tue, Apr 14, 2015 at 5:17 PM, Catalin Marinas wrote: > On Tue, Apr 14, 2015 at 02:49:04PM -0500, Kumar Gala wrote: >> On Apr 14, 2015, at 11:36 AM, Mark Rutland wrote: >> > On Fri, Apr 10, 2015 at 11:05:29AM +0100, Catalin Marinas wrote: >> >> On Thu, Apr 09, 2015 at 12:37:06PM -0500, Kumar Gala wrote: >> >>> This patch set adds support for SMP boot on the MSM8x16 family of Qualcomm SoCs. >> >>> >> >>> To support SMP on the MSM8x16 SoCs we need to add ARMv8/64-bit SCM interfaces to >> >>> setup the boot/release addresses for the secondary CPUs. In addition we need >> >>> a uniquie set of cpu ops. I'm aware the desired methods for booting secondary >> >>> CPUs is either via spintable or PSCI. However, these SoCs are shipping with a >> >>> firmware that does not support those methods. >> >> >> >> And the reason is? Some guesses: >> >> >> >> a) QC doesn't think boot interface (and cpuidle) standardisation is >> >> worth the effort (to put it nicely) >> >> b) The hardware was available before we even mentioned PSCI >> >> c) PSCI is not suitable for the QC's SCM interface >> >> d) Any combination of the above >> >> >> >> I strongly suspect it's point (a). Should we expect future QC hardware >> >> to do the same? >> >> >> >> You could argue the reason was (b), though we've been discussing PSCI >> >> for at least two years and, according to QC press releases, MSM8916 >> >> started sampling in 2014. >> >> >> >> The only valid reason is (c) and if that's the case, I would expect a >> >> proposal for a new firmware interface protocol (it could be PSCI-based), >> >> well documented, that can be shared with others that may encounter the >> >> same shortcomings. >> > >> > There's no need to even fork PSCI. The PSCI specification will evolve >> > over time as vendors request changes and we try to accomodate them. >> > >> > If there's something that PSCI doesn't do that you need it to, contact >> > ARM. Other vendors already have. > > Mostly yes but there may be valid reasons for not being able to use > PSCI. The spin-table method is still a firmware interface, though not > necessarily secure (a.k.a. SMC-based). The ACPI parking protocol is > another and, who knows, maybe we define a way to park CPUs back to > firmware without SMC calls (when EL3 is not available). > >> But what is someone to do between the period of getting PSCI spec >> updated and needing to ship a product with firmware? >> >> The take still sounds like if you don’t implement an exact version of >> PSCI you are screwed from being supported in the upstream ARM64 >> kernel. > > These are silly arguments. There is a big difference between "we > couldn't get the firmware implementing the standard for the early > silicon but we are working on fixing it for future revisions" vs. "we > don't give a s**t about these standards, the kernel must be inclusive". > So please make up your mind on which direction you want to pursue. > Just speaking as an outsider to this topic, but seems like most/all tablets/phones/etc ship with signed firmware. Which means for most of the population, upgrading the firmware to a new version which did support the standard (assuming it existed), isn't really an option on our devices, any more than fixing buggy acpi tables is on our laptops.. BR, -R > -- > Catalin > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/