From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752328AbbESCvl (ORCPT ); Mon, 18 May 2015 22:51:41 -0400 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:51271 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbbESCvj (ORCPT ); Mon, 18 May 2015 22:51:39 -0400 MIME-Version: 1.0 In-Reply-To: <1431770926.5748.41.camel@hellion.org.uk> References: <1431583811-25780-1-git-send-email-wens@csie.org> <1431770926.5748.41.camel@hellion.org.uk> From: Chen-Yu Tsai Date: Tue, 19 May 2015 10:51:12 +0800 Message-ID: Subject: Re: [linux-sunxi] [RFC 0/7] ARM: sun9i: SMP support with Multi-Cluster Power Management To: Ian Campbell Cc: Chen-Yu Tsai , Maxime Ripard , Nicolas Pitre , Dave Martin , linux-arm-kernel , linux-kernel , linux-sunxi Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 16, 2015 at 6:08 PM, Ian Campbell wrote: > On Thu, 2015-05-14 at 14:10 +0800, Chen-Yu Tsai wrote: >> This is my attempt to support SMP and CPU hot plugging on the Allwinner >> A80 SoC. The A80 is a big.Little processor with 2 clusters of 4x Cortex-A7 >> and 4x Cortex-A15 cores. > > I thought there was a preference these days to support this sort of > thing via support PSCI in the firmware, which allows for other things > such as non-secure-world etc. Ideally, yes. However, U-boot only has minimal A80 support for now. Also, multi-cluster support is not as simple as what we had for the A20. The kernel already has common multi-cluster code. With it we can do full SMP/hotplug support. Kernel code is also easier to write and debug than PSCI, which ATM is all per-platform assembly. Also, my A31 and A23 PSCI implementations still need some work. ChenYu