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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 B3C65C43603 for ; Sun, 8 Dec 2019 03:43:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67895208C4 for ; Sun, 8 Dec 2019 03:43:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rbWooSis" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726418AbfLHDnq (ORCPT ); Sat, 7 Dec 2019 22:43:46 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:35196 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbfLHDnq (ORCPT ); Sat, 7 Dec 2019 22:43:46 -0500 Received: by mail-pg1-f193.google.com with SMTP id l24so5352422pgk.2 for ; Sat, 07 Dec 2019 19:43:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sWMtClNl8XwNKgQLggPkzKJERS5n6iPDCia4dn3R50w=; b=rbWooSisp6hgP51Y4NVm1IM0LYunQpQJB23NGGnmuXhFai0T7hZz/nFZCuT8sElY4b 5vP4VSWmuwxTDBqvhUi+Y0Hx7T2/X4RScgTqmfnZ4L/1j5UHCe7bXK3HLIW8n+nyEjFQ Nx3bLhRUXXnvdXOI5jzYqaPwwLHTB2QtJCv8HOVRU1fjTpBAWOIYhXqTseojDP1paO4v wlkjZAqSpDlEMxp+bUBzcZsSm6b4NxQxFJdZlgN8WHqAjPqXg3wTlG7ppyGJniza93r9 Ldp8Z+zM7iBVXFt2c4joZ0HAbf4O5VMG6jG8tD6PZKr8ABq/cZVhgEa3T32a8jL29K5G Z3LA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=sWMtClNl8XwNKgQLggPkzKJERS5n6iPDCia4dn3R50w=; b=XcEM7qJKvFS/OhTVF2B8xgCuS+94Sn2nwamtSWAJuddHCMhYG5dURcdGVCVrH1DWeH KQJtCZLwIS4i2Cing55UOM5MYb6k5Ob1zrPtrD1+cGCHfx6J/afEyvE4VG+0VDmoJsPW IR8iW9S5irozp9J8MlZ/0EGrZdLDds2oVNVkEC6PKI6wz/TVIFurvUzM+DIkkzgAloUE pvdg6jBXoSQ6wEPgqZd5bXxgquKO5DqNRnj+ntE/BHeaV7Jb2wMoJ4H+e+KLFh9kVxAO 3eTSnnfPredsDGYE0R/Vq7hBTkMD8Is6b4Rm7djUYkdGzDWcuvjP6a5mB1l7ZqXUfyIr XJlA== X-Gm-Message-State: APjAAAXhWHWiRjOuBUY2QB70a4TGm5R0imoWa9H8JdAKiwSPjtoWiSLe yD5AGhC4RhcSFU7sP44yrsWyVfUS X-Google-Smtp-Source: APXvYqwNNfPqYmmxrsETh0KM2KnNvsPM/eQhjwhYoGWm8zCXl0bXb+I3A//pPGXuCXcpK5lWLSXVCg== X-Received: by 2002:a63:1c5e:: with SMTP id c30mr12387111pgm.30.1575776625796; Sat, 07 Dec 2019 19:43:45 -0800 (PST) Received: from sol (220-235-109-115.dyn.iinet.net.au. [220.235.109.115]) by smtp.gmail.com with ESMTPSA id i13sm20418139pgr.48.2019.12.07.19.43.43 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 07 Dec 2019 19:43:45 -0800 (PST) Date: Sun, 8 Dec 2019 11:43:40 +0800 From: Kent Gibson To: Russell King Cc: Linus Walleij , Bartosz Golaszewski , linux-gpio@vger.kernel.org Subject: Re: [PATCH] gpiolib: fix up emulated open drain outputs Message-ID: <20191208034340.GA9333@sol> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Sat, Dec 07, 2019 at 04:20:18PM +0000, Russell King wrote: > gpiolib has a corner case with open drain outputs that are emulated. > When such outputs are outputting a logic 1, emulation will set the > hardware to input mode, which will cause gpiod_get_direction() to > report that it is in input mode. This is different from the behaviour > with a true open-drain output. > > Unify the semantics here. > > Suggested-by: Linus Walleij > Signed-off-by: Russell King > --- > drivers/gpio/gpiolib.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 32c2048deb8c..70c60aac41cc 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -220,6 +220,14 @@ int gpiod_get_direction(struct gpio_desc *desc) > chip = gpiod_to_chip(desc); > offset = gpio_chip_hwgpio(desc); > > + /* > + * Open drain emulation using input mode may incorrectly report > + * input here, fix that up. > + */ > + if (test_bit(FLAG_OPEN_DRAIN, &desc->flags) && > + test_bit(FLAG_IS_OUT, &desc->flags)) > + return 0; > + What about the FLAG_OPEN_SOURCE case? Kent. > if (!chip->get_direction) > return -ENOTSUPP; > > -- > 2.20.1 >