From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF96AC433DB for ; Thu, 11 Mar 2021 16:12:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AECD364FEB for ; Thu, 11 Mar 2021 16:12:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234360AbhCKQM0 (ORCPT ); Thu, 11 Mar 2021 11:12:26 -0500 Received: from mail-out.m-online.net ([212.18.0.10]:57202 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234465AbhCKQL4 (ORCPT ); Thu, 11 Mar 2021 11:11:56 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4DxDV06DYQz1s00y; Thu, 11 Mar 2021 17:11:52 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4DxDV0432hz1qr4l; Thu, 11 Mar 2021 17:11:52 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id jnJYO_qSd5et; Thu, 11 Mar 2021 17:11:50 +0100 (CET) X-Auth-Info: 2KuBOCaE/sL/z2h12qu6ViGM9U9yOLCzuzHVP39GOc4= Received: from [IPv6:::1] (p578adb1c.dip0.t-ipconnect.de [87.138.219.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Thu, 11 Mar 2021 17:11:50 +0100 (CET) Subject: Re: [Linux-stm32] [PATCH v2 00/14] Introduce STM32MP1 RCC in secured mode To: Ahmad Fatoum , Alexandre TORGUE , Alexandre TORGUE , "Alex G." , Gabriel FERNANDEZ - foss , Michael Turquette , Stephen Boyd , Rob Herring , Maxime Coquelin , Philipp Zabel , Etienne CARRIERE Cc: "devicetree@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-clk@vger.kernel.org" References: <20210126090120.19900-1-gabriel.fernandez@foss.st.com> <2e04f814-b694-119d-fe8a-13e6df129536@gmail.com> <463dafed-ec60-cd9a-33d2-ba118a6af629@foss.st.com> From: Marek Vasut Message-ID: Date: Thu, 11 Mar 2021 17:11:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 3/11/21 3:41 PM, Ahmad Fatoum wrote: > Hello, Hi, > On 11.03.21 15:02, Alexandre TORGUE wrote: >> On 3/11/21 12:43 PM, Marek Vasut wrote: >>> On 3/11/21 9:08 AM, Alexandre TORGUE wrote: >>>> 1- Break the current ABI: as soon as those patches are merged, stm32mp157c-dk2.dtb will impose to use >>>> A tf-a for scmi clocks. For people using u-boot spl, the will have to create their own "no-secure" devicetree. >>> >>> NAK, this breaks existing boards and existing setups, e.g. DK2 that does not use ATF. >>> >>>> 2-As you suggest, create a new "secure" dtb per boards (Not my wish for maintenance perspectives). >>> >>> I agree with Alex (G) that the "secure" option should be opt-in. >>> That way existing setups remain working and no extra requirements are imposed on MP1 users. Esp. since as far as I understand this, the "secure" part isn't really about security, but rather about moving clock configuration from Linux to some firmware blob. >>> >>>> 3- Keep kernel device tree as they are and applied this secure layer (scmi clocks phandle) thanks to dtbo in >>>> U-boot. >>> >>> Is this really better than >>> #include "stm32mp15xx-enable-secure-stuff.dtsi" >>> in a board DT ? Because that is how I imagine the opt-in "secure" option could work. >>> >> >> Discussing with Patrick about u-boot, we could use dtbo application thanks to extlinux.conf. BUT it it will not prevent other case (i.e. TF-A which jump directly in kernel@). So the "least worst" solution is to create a new "stm32mp1257c-scmi-dk2 board which will overload clock entries with a scmi phandle (as proposed by Alex). > > I raised this issue before with your colleagues. I still believe the correct way > would be for the TF-A to pass down either a device tree or an overlay with the > actual settings in use, e.g.: > > - Clocks/Resets done via SCMI > - Reserved memory regions > > If TF-A directly boots Linux, it can apply the overlay itself, otherwise it's > passed down to SSBL that applies it before booting Linux. That sounds good and it is something e.g. R-Car already does, it merges DT fragment from prior stages at U-Boot level and then passes the result to Linux. So on ST hardware, the same could very well happen and it would work for both non-ATF / ATF / ATF+TEE options.