From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Gala Subject: Re: [RFC PATCH 0/5] Add smp booting support for Qualcomm ARMv8 SoCs Date: Tue, 14 Apr 2015 14:49:04 -0500 Message-ID: <07185B2C-3F37-4E70-9096-1EF5EA8D68CE@codeaurora.org> References: <1428601031-5366-1-git-send-email-galak@codeaurora.org> <20150410100529.GA6854@e104818-lin.cambridge.arm.com> <20150414163613.GM28709@leverpostej> Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20150414163613.GM28709@leverpostej> Sender: linux-arm-msm-owner@vger.kernel.org To: Mark Rutland Cc: Catalin Marinas , "linux-arm-msm@vger.kernel.org" , "devicetree@vger.kernel.org" , "abhimany@codeaurora.org" , Will Deacon , "linux-kernel@vger.kernel.org" , "arm@kernel.org" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org > On Apr 14, 2015, at 11:36 AM, Mark Rutland wro= te: >=20 > 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 Q= ualcomm SoCs. >>>=20 >>> 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 additi= on we need >>> a uniquie set of cpu ops. I'm aware the desired methods for bootin= g secondary >>> CPUs is either via spintable or PSCI. However, these SoCs are ship= ping with a >>> firmware that does not support those methods. >>=20 >> And the reason is? Some guesses: >>=20 >> 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 >>=20 >> I strongly suspect it's point (a). Should we expect future QC hardwa= re >> to do the same? >>=20 >> You could argue the reason was (b), though we've been discussing PSC= I >> for at least two years and, according to QC press releases, MSM8916 >> started sampling in 2014. >>=20 >> 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-bas= ed), >> well documented, that can be shared with others that may encounter t= he >> same shortcomings. >=20 > 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. >=20 > If there's something that PSCI doesn't do that you need it to, contac= t > ARM. Other vendors already have. But what is someone to do between the period of getting PSCI spec updat= ed and needing to ship a product with firmware? The take still sounds like if you don=E2=80=99t implement an exact vers= ion of PSCI you are screwed from being supported in the upstream ARM64 = kernel. - k --=20 Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora For= um, a Linux Foundation Collaborative Project