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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA0CCC6379F for ; Tue, 10 Jan 2023 09:31:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231807AbjAJJbI (ORCPT ); Tue, 10 Jan 2023 04:31:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232263AbjAJJa4 (ORCPT ); Tue, 10 Jan 2023 04:30:56 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 690B6B45 for ; Tue, 10 Jan 2023 01:30:52 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id jn22so12540643plb.13 for ; Tue, 10 Jan 2023 01:30:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20210112.gappssmtp.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=MPK8Pcd1KnxbIqf6AZnIbTulBe6CihDk4OzBMX0CQsA=; b=rSXAadCpOXwSRQXKprH1Oae0tV4q9g6xL1Yfv6tAov/VkM/cUU2Px8vZo69Gfxwae+ hT5rWatOGwsd80nmtgleJxTssxGu0OUIDYA9N3Kc17b2eeiWrjkmQX+TSzhP5qqlmUsh t/sVOMWsSWi5CfDFsoKuTLUyj1m6MSuPkgHEfc5aauUkjd78mZNOH6D+nZbbiXM7unKN BZQOMCEs/m0Ij9X0ZyQ0O5hwYOr2i6IGrhRvYV9YhEJ28UV+J7fHtE0BgZehuCQE9b0D 9tdYhInjbkjqQ/4CwGDQIlV5uDOGOLS+yDnhz0x9MNiE1g0W+7j5/of/bQkIQRmQexaa Y1vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=MPK8Pcd1KnxbIqf6AZnIbTulBe6CihDk4OzBMX0CQsA=; b=O2utlkmYy5Gfhj0C73Wlmbb7uDqIZDPKv3oOhRozDxBcSA5n13NsMcaraeb6eCa1WX 0Dxwf5DOL06+jfhjd0K/wVV0t43zpGGHccj/tYfAdTmei29JttiZ2ob3hz5sPEkw+Kgm QIMIXEJahMxaaQkeOe7z+wAo08aHbiYvNTeHvPAeQBJSgaOP3hHqbTV05ilxYryWPvWB RskXTAtHAUrZtNZvxUV31cfEtvbbQPoxbxWRH00A5iwlC8LgtqqqnjIdF82UiHFsn6Yy sczL88XVBtTjROkCxM4LsrId9lCW2xpYgLF1Bd8VH5ekBug3XFQoqiYzousnjPCYqfsP VyHw== X-Gm-Message-State: AFqh2kpAXSo6KJzoLUm/SPb8RAp+mM1R8ZWzfnTvThA2IbTKRTj/2iIm bcvuBbK6MQwnX3BzjdOpTxaCcw== X-Google-Smtp-Source: AMrXdXuZSa+rV/0+yMaG6ICmG8FWoorYjfeL96GGckbKJke1oTTmQAFftVGi/4o7yksx/xoxLoOO+A== X-Received: by 2002:a17:902:b713:b0:191:2a9c:52a1 with SMTP id d19-20020a170902b71300b001912a9c52a1mr69151667pls.19.1673343051900; Tue, 10 Jan 2023 01:30:51 -0800 (PST) Received: from x1 ([2601:1c2:1002:ab0:18c0:a4d5:b5ff:3aeb]) by smtp.gmail.com with ESMTPSA id ik22-20020a170902ab1600b001925d6fdfebsm7505744plb.299.2023.01.10.01.30.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jan 2023 01:30:51 -0800 (PST) Date: Tue, 10 Jan 2023 01:33:21 -0800 From: Drew Fustini To: Linus Walleij Cc: Geert Uytterhoeven , Biju Das , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Thierry Reding , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , linux-renesas-soc@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, Chris Paterson , Biju Das , Prabhakar Mahadev Lad Subject: Re: [PATCH v5 0/9] Add RZ/G2L POEG support Message-ID: References: <20221215213206.56666-1-biju.das.jz@bp.renesas.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Jan 10, 2023 at 09:09:21AM +0100, Linus Walleij wrote: > On Mon, Jan 9, 2023 at 2:41 PM Geert Uytterhoeven wrote: > > On Mon, Jan 9, 2023 at 2:16 PM Linus Walleij wrote: > > > On Tue, Jan 3, 2023 at 10:01 AM Geert Uytterhoeven wrote: > > > > > If this should go into sysfs we should probably create something > > > > > generic, such as a list of stuff to be exported as sysfs switches. > > > > > > > > > > It generally also looks really dangerous, which is another reason > > > > > for keeping it in debugfs. It's the big hammer to hurt yourself with, > > > > > more or less. > > > > > > > > Yes, generic would be nice. Anyone familiar with other hardware > > > > that could make use of this? > > > > > > Drew was using this for Beagle Bone IIRC, Drew? > > > > Yes, that's what I remember, too. And I tested it on Koelsch. > > > > But again, that's for debugging purposes. For non-debugging > > operation, we need something different. > > Actually Drew's usecase wasn't for debugging. It was kind-of production, > but it was for "one-offs" such as factory lines and other very specific-purpose > embedded. > > The placement in debugfs was mostly because it is fragile and dangerous. > > Yours, > Linus Walleij For the BeagleBone, the use case for selecting pin fuctions from userspace with pinmux-select in debugfs is to allow for rapid prototyping situations such as breadboarding. Our Debian install on the boards has an utility named config-pin that allows the user to select between defined pinctrl states for each pin on the expansion header. Some users like this as it means they do not need to constantly be editing device tree files and rebooting while protoyping. I agree that this is not a fool-proof scheme but Beaglebones have been shipping with this functionality for many years without any significant problems that I'm aware of. I do admit that it is possible for someone to potentially damage circuits with this flexibility, so having a warning in the kernel log like Andy suggested elsewhere in this thread might be a good idea. Thanks, Drew