From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f178.google.com (mail-yb1-f178.google.com [209.85.219.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 610BF7C for ; Sat, 12 Feb 2022 16:55:01 +0000 (UTC) Received: by mail-yb1-f178.google.com with SMTP id l125so829492ybl.4 for ; Sat, 12 Feb 2022 08:55:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=biysQ3IsY2w+NMb+t1WSQWW4AmDXHDFl1wRiCvR4z4A=; b=Mz/hHNUOtjKmsHGh20Qo0guG/Qg2wiAB4AvUgN+QYwQlsg/MI+Gk1tdkNMVhkz7FvF uLUlG6rpT/QCxyF24eGIFwno1CC0xAft6LNiQuINyo4fUf71zRpz5OZMNwxjg+C3kWbl kBmd9gngoENaGRXCIMowhfp3a0hSjrETIBQAcr/yZidmjucqfrUExAjhb1g/bRr8k4H2 2NeuWZrgGZipVP0AVBBafdQ+G0lKITdtiyw1in/MoS0XBe1dxm7NavR4O8t5YNxfka4G vjGjPYHYgCemAYBBS/Q6VUSUVq2b0FTVHhcwjcctT0TNO7x3G3bMtzbCQaB6swrbAP2Z Uuyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=biysQ3IsY2w+NMb+t1WSQWW4AmDXHDFl1wRiCvR4z4A=; b=6B+g3/NzmXFDEluxK1yTiGuwy+FQe9daVo+WNTJ+tDm7s+B9Ih2/T4sxOrauu/ttYF F8fTl3tGpJspGDbGBx2Nfem/RbJuebEn5Huck7DOwZTdZ/tJo/5HgOYJt/49l+k7mKaG fyq6ewkLxt1Vs9QsPQdYH2K6pX8ikUUg5vNHWMtPO+R+gNt42wQwi8srLpui2O4yrUqg nSdIU03otHYLjnLyvi2YfvaMu0WfbbDq0MrvMBCRlyfkRx8tpPnGcocXif8gYEPTyHWO 8Dkt1yDTtst21F9gP0fexZTq6E+4l4eiQkTc23sZR2LdvSUtnte8SAUk2yMdCD09zEGb yZMA== X-Gm-Message-State: AOAM531ytRmDhMvw5tiMhzaSLrf0muOp8qqi6jP1xV0FPe4sSRJommyj fXha4o/iOMZKud7nJaOMnVI6LfLscbjhKxFAaryP6w== X-Google-Smtp-Source: ABdhPJxY7wL1B0Tp9SS789YZZRkRDCVX/nCvjhJ9T1/d7umwF8iHCoCHKWI/kl7Ai8sZPm2pZ8xwp5LVQvKKElkeXTw= X-Received: by 2002:a5b:f4b:: with SMTP id y11mr5781546ybr.634.1644684900080; Sat, 12 Feb 2022 08:55:00 -0800 (PST) Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20211217153555.9413-1-marcelo.jimenez@gmail.com> In-Reply-To: From: Linus Walleij Date: Sat, 12 Feb 2022 17:54:48 +0100 Message-ID: Subject: Re: [PATCH] gpio: Revert regression in sysfs-gpio (gpiolib.c) To: Marcelo Roberto Jimenez Cc: stable , regressions@lists.linux.dev, Bartosz Golaszewski , "open list:GPIO SUBSYSTEM" , Thierry Reding , Vidya Sagar , Geert Uytterhoeven , Stephen Rothwell , Edmond Chung , Andrew Chant , Will McVicker , Sergio Tanzilli Content-Type: text/plain; charset="UTF-8" On Fri, Feb 11, 2022 at 11:36 PM Marcelo Roberto Jimenez wrote: > > Which devicetree or boardfile in the upstream Linux kernel is this system > > using? > > arch/arm/boot/dts/at91-ariettag25.dts So this system was added in 2015 which is the same year that we marked the GPIO sysfs ABI obsolete: commit fe95046e960b4b76e73dc1486955d93f47276134 Author: Linus Walleij Date: Thu Oct 22 09:58:34 2015 +0200 gpio: ABI: mark the sysfs ABI as obsolete Why is this system which was clearly developed while we deprecated the sysfs ABI so dependent on it? I am curious about the usecases and how deeply you have built yourselves into this. > In any case, the upstream file should be enough to test the issue reported here. The thing is that upstream isn't super happy that you have been making yourselves dependent on features that we are actively discouraging and then demanding that we support these features. Anyway, what is wrong with using the GPIO character device and libgpiod on this system? What kind of userspace are you creating that absolutely requires that you use sysfs? I hope not one of these? https://docs.kernel.org/driver-api/gpio/drivers-on-gpio.html Here is some info about what we have been doing with the GPIO character device: https://docs.kernel.org/driver-api/gpio/using-gpio.html https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/ Here is Bartosz presenting it: https://www.youtube.com/watch?v=BK6gOLVRKuU Since I patched the kernel such that you cannot activate the sysfs ABI without also activating the character device I *know* that you have it on your system. Yours, Linus Walleij