Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964970AbbDPJnF (ORCPT ); Thu, 16 Apr 2015 05:43:05 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:35735 "EHLO mx08-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964950AbbDPJmt (ORCPT ); Thu, 16 Apr 2015 05:42:49 -0400 Message-ID: <552F83F0.1090403@st.com> Date: Thu, 16 Apr 2015 11:42:08 +0200 From: Maxime Coquelin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Arnd Bergmann , Florian Fainelli CC: , , , , , Subject: Re: Allowing reset controllers before SMP initialization (on ARM)? References: <552F0786.2000505@gmail.com> <2592960.UsK4Hr7GSl@wuerfel> In-Reply-To: <2592960.UsK4Hr7GSl@wuerfel> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.201.23.80] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.13.68,1.0.33,0.0.0000 definitions=2015-04-16_04:2015-04-15,2015-04-16,1970-01-01 signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1738 Lines: 42 Hi Florian, Arnd, On 04/16/2015 10:04 AM, Arnd Bergmann wrote: > On Wednesday 15 April 2015 17:51:18 Florian Fainelli wrote: >> Hi, >> >> In order to support initialization of the secondary core on BCM63138 >> SoCs, I would want to utilize a reset controller to release the >> secondary CPU from reset [1]. >> >> Here are multiple options: >> >> - expose a custom function which registers the reset controller platform >> driver as early as possible, which is probably acceptable, but also >> requires the DT machine descriptor to populate the platform bus earlier, >> which we could completely avoid > I think populating the platform bus earlier is not realistic, that > would break lots of existing dependencies. In particular, we can't > do it much earlier because it has to be done after the platform bus > itself is instantiated. > >> - have a OF_DECLARE_RESET_CONTROLLER() which is running fairly early >> during boot, such that we can utilize reset controllers are early as >> possible, before any initcall level, and before SMP initialization is >> kicking in > We've added a couple of those, and it could be done here, but putting > them in the right order is a bit tricky, and I think we can avoid it. I have already proposed a OF_DECLARE_RESET_CONTROLLER() implementation: https://lkml.org/lkml/2015/2/20/395 I needed it for the STM32 timers, but it was not accepted. Now, I perform the timers reset in the bootloader, but it shouldn't work in your case. Kind regards, Maxime -- 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/