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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 F3652C47404 for ; Fri, 11 Oct 2019 13:49:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C877C206A1 for ; Fri, 11 Oct 2019 13:49:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LO9BrhRv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727589AbfJKNtt (ORCPT ); Fri, 11 Oct 2019 09:49:49 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:41889 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728027AbfJKNtt (ORCPT ); Fri, 11 Oct 2019 09:49:49 -0400 Received: by mail-pg1-f193.google.com with SMTP id t3so5835490pga.8 for ; Fri, 11 Oct 2019 06:49:48 -0700 (PDT) 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=FkkdXZCKufhPfpJuUrLtjBXl+mZnj5fRvjRYErS4ujs=; b=LO9BrhRvZE7epUFiyqyJYbhp4xwnr7ZMuGcnmyGsHQVMOxE2BJJVd/PpyjVsJU5H+X RIploftSJdisD5SlkXJMar7mS09q3WNrg6mgkenJIfK7GBSqSQBAKbajSmXFAMaOX0Nw m4BAmOp2wmSBFwMP37L1WK9Gphh+R0Pc5okMqSdbg/gRR0/gAEjvcLlVONXX+XUkFeYM M9IAg+Jz9WTBWjo7pOEqHYyufpMz7nInGyKClJNyLrlzEcxHwnj3hIBxL4Kv1hoMF3DV 3RYnaSntHIUJYBNBLp7WootTs0MkO0bUmZJgVbgeo/Vw3e7umL3wXgtTf7NbejIrTiX6 0YQA== 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=FkkdXZCKufhPfpJuUrLtjBXl+mZnj5fRvjRYErS4ujs=; b=r3BdKyMEj4uBO1i33tx1WsmXtgkxcG4o5GDYZPfVeD21yh5G95Vzd5tJH4gMu+MXZM CJ7/ag8Uz6g7CxU8rYbudAQsz3oOFt8tMGfJFt0LY3flOg7eCaG7S32Z46uYUynAlTeq H3aJMmZem126mL36Lkkcv83KsBbn2sHIC/+Lnv41Of1Q9d8IrWadazdZ/olmVnA+Jb3c Ul6xFukpOwzNlZ/SA49tL2OQ9h8trfyL17XQitVK+fN4VzqqqYgBNJZRB6WR56chdIq0 KDVuau41Cc/8uCWLrnl1+4nD6Klhdnlr1g2xumsmivNOO72A9fDS36Y8L/c7aMwRh7M9 7j9Q== X-Gm-Message-State: APjAAAX6F4aUyfTIGkrRao+AWkKOkn14I1fOPFno8egXGyjvTcwtQCU1 O2xhtCGfx2TlOsaxK7ERtEQ= X-Google-Smtp-Source: APXvYqwxt1tDKSuHujrWhL+ecRzB67r6QKu7VRMrxsLk5ICihQJtRjFFz0E7qPxMfRrz4yC+dP9thQ== X-Received: by 2002:a65:6817:: with SMTP id l23mr16727719pgt.338.1570801788090; Fri, 11 Oct 2019 06:49:48 -0700 (PDT) Received: from sol (220-235-84-126.dyn.iinet.net.au. [220.235.84.126]) by smtp.gmail.com with ESMTPSA id l192sm19689557pga.92.2019.10.11.06.49.44 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 11 Oct 2019 06:49:47 -0700 (PDT) Date: Fri, 11 Oct 2019 21:49:41 +0800 From: Kent Gibson To: Drew Fustini Cc: Bartosz Golaszewski , "open list:GPIO SUBSYSTEM" , Linus Walleij Subject: Re: [RFC] gpio: expose pull-up/pull-down line flags to userspace Message-ID: <20191011134941.GA29042@sol> References: <20191008235626.GA10744@sol> <20191009002211.GA11168@sol> <20191009065524.GA4061@sol> <20191009133037.GA17244@x1> <20191009235938.GA10263@sol> <20191010101421.GA14692@sol> 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 Fri, Oct 11, 2019 at 03:06:41PM +0200, Drew Fustini wrote: > Hi Kent, > > I noticed there are some additional commits in your branch including: > 7f0bcb88f583 pull up/down on output is actually a valid option > Yeah pulls make no sense for push pull lines, but while looking into disabling bias I discovered that there are some chips that support pull-up/down for open drain/source outputs. It seemed reasonable to support them rather than reject them outright, hence the reversal. > Do you know what the result would be when the line is an output? > Behaviour would depend on the driver and chip. I'm assuming the user would only request combinations that make sense and that the driver would reject any combinations that might have unfortunate results. I'm working on improving my git-fu to collect the pull changes from that branch, and hope to mail out a patch set shortly. Cheers, Kent.