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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 323B3C388F9 for ; Tue, 27 Oct 2020 12:16:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D417B24671 for ; Tue, 27 Oct 2020 12:16:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603800992; bh=rHy7m3RuiJVB+20ux7B22H/jeahOgDzJQVxUUqsPONE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=uGaHOV0aZ7Qy5ckR/whcAIy4nPCBQvT73Bw2x1F7wnL9cAMAegTBnF97f4y4jEO1+ z0a1PFNuXpkeehhPlrC+rXIo/+xYCfev2N2Zz5yatYLfa1ch/9BklkDGpCvR+38JiF u05kDsaQeiNly3Mit5T7UxgQOR+qnoEZjap2UnRM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2899660AbgJ0MQ1 (ORCPT ); Tue, 27 Oct 2020 08:16:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:59540 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2899633AbgJ0MQK (ORCPT ); Tue, 27 Oct 2020 08:16:10 -0400 Received: from mail-oo1-f52.google.com (mail-oo1-f52.google.com [209.85.161.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 889B324677; Tue, 27 Oct 2020 12:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603800969; bh=rHy7m3RuiJVB+20ux7B22H/jeahOgDzJQVxUUqsPONE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=nnslobMGiXfBKFGnGsYxOuqPAeWLHs9VXT5qE++xWWTVdGmCplAti2v3iFFzFaPmh Aw2AlXxRpu2V1H8IMkogfIpWAvF+1iZ4KdGcyGqB3Mdx5Q8hdz0p0oleDQMcwMkW7I Tm3oL/qRKuH7Eee2jicv4D49KxzNLOagtRWKlDNQ= Received: by mail-oo1-f52.google.com with SMTP id n2so268401ooo.8; Tue, 27 Oct 2020 05:16:09 -0700 (PDT) X-Gm-Message-State: AOAM5302FloAnbSnrVnjFibVSewxkGq+XY0OOAffVn2uXawmEJJuSnL9 MyYhwfcr0sycV4BZwbdjNuT8yqffpH/Hpu/i9g== X-Google-Smtp-Source: ABdhPJwWNPIQlF6Bp7SJfw0BWlotFu1Nk1SaBiaHNR8Jk/NmGn35wJqO0jl1Ihg5ANtyL/n3D9IZ22eRLIBU/rPXk3E= X-Received: by 2002:a4a:d453:: with SMTP id p19mr1528328oos.50.1603800968782; Tue, 27 Oct 2020 05:16:08 -0700 (PDT) MIME-Version: 1.0 References: <20201021102855.18026-1-a.fatoum@pengutronix.de> <20201026143656.GA118160@bogus> <23e423ba-25f2-c3ed-ea65-2c2d86ae9522@pengutronix.de> In-Reply-To: <23e423ba-25f2-c3ed-ea65-2c2d86ae9522@pengutronix.de> From: Rob Herring Date: Tue, 27 Oct 2020 07:15:57 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/2] dt-bindings: arm: stm32: add simple-mfd compatible for tamp node To: Ahmad Fatoum Cc: Maxime Coquelin , Alexandre Torgue , Christophe Roullier , Sascha Hauer , Arnaud Pouliquen , devicetree@vger.kernel.org, "moderated list:ARM/STM32 ARCHITECTURE" , linux-arm-kernel , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 26, 2020 at 4:30 PM Ahmad Fatoum wrote: > > Hello Rob, > > On 10/26/20 3:36 PM, Rob Herring wrote: > > On Wed, Oct 21, 2020 at 12:28:55PM +0200, Ahmad Fatoum wrote: > >> The stm32mp1 TAMP (Tamper and backup registers) does tamper detection > >> and features 32 backup registers that, being in the RTC domain, may > >> survive even with Vdd switched off. > >> > >> This makes it suitable for use to communicate a reboot mode from OS > >> to bootloader via the syscon-reboot-mode binding. Add a "simple-mfd" > >> to support probing such a child node. The actual reboot mode > >> node could then be defined in a board.dts or fixed up by the bootloader. > > > > 'simple-mfd' implies there is no dependency on the parent node for the > > child (such as the regmap perhaps). Is that the case here? > > No, there's a dependency and the Linux driver does syscon_node_to_regmap > on the device tree node's parent but that's how the syscon-reboot-mode binding > is documented: > > The SYSCON mapped register is retrieved from the > parental dt-node plus the offset. So the SYSCON reboot-mode node > should be represented as a sub-node of a "syscon", "simple-mfd" node. > > How would you prefer this being done instead? Well, probably the syscon driver could just probe any children, but I'm not sure if that would break anyone. So I guess fine as-is. Reviewed-by: Rob Herring Rob