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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 294BCC5DF9E for ; Thu, 29 Oct 2020 18:11:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C58922087D for ; Thu, 29 Oct 2020 18:11:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="sTXYZLcJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725798AbgJ2SLv (ORCPT ); Thu, 29 Oct 2020 14:11:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725995AbgJ2SKH (ORCPT ); Thu, 29 Oct 2020 14:10:07 -0400 Received: from mail-oi1-x242.google.com (mail-oi1-x242.google.com [IPv6:2607:f8b0:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2E99C0613CF for ; Thu, 29 Oct 2020 11:10:06 -0700 (PDT) Received: by mail-oi1-x242.google.com with SMTP id j7so3925464oie.12 for ; Thu, 29 Oct 2020 11:10:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=baxZPWBaI3mgJK17htQYs6QNkJcd1AoLPEP3SIpgux4=; b=sTXYZLcJU7aTrNeIYGm20sqABLnbOXu6IvnchI1ofm+e5jocswq+TN9xTBx7c07ji6 jJtfgfl/4y2RlQESdyWH1vhD8/Jj7RdVZN5CUiXHNl+1uLkAf2FTQl//FudX95G/Evjc lOpgc3ckG0UBHOVpZTm3u1/gw0uZlFjCVJ4s5rmg3XcW2z38zBJzaGF1LO/DW0TtC1fi KuPGvHVWcbDZfsqeM92/VP6sf397BR0vSiyUZ7vLOuCNeBHoTyFazoYblBOfmJLhmodq pNoFZpeLC0nAB/M8Eu1PUd95EP+/aI/T3RYK5vDRhGaFDsJTDuxVIFqiLQd3Es1hJZOI gvOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=baxZPWBaI3mgJK17htQYs6QNkJcd1AoLPEP3SIpgux4=; b=M8//MU/sQAzW3pZ71H4xiGH2Adq+IrEshFHM9y9NC1j0U8AjrHd/0ITLhDaImeP22D 9wK9lMUn0Vy6fQNWgrm1j+efRLuhrHzovH2FVFpi6Db0OaIzmbaQ7l7bLIcKgVIsSTmQ qJ2iJI0nY5vDe/k4YLocy94eXRsVTPVpVJ+UcU6pOQWzcY3fsE9iQAEmCqO6LF8ULd4s 84BRh5DIvUvYAC7xjyS5C1j8jZGpMMCYdU4a3uZ37eLgRm4cjHvoiJ2QyhFeLrnN1mLa qmC3X2nyyifD+QhxsI5NLwoTHK2g03aI06n2uMgKBQSd8BUWy9TjfWAnfa1Ijfa3PKCr dSJA== X-Gm-Message-State: AOAM530COs/sMrLKbq3w2vy22m4dnrPnQvN0BfMkpZOcsvzYy+L18rv0 7+QDERCF9HPf9+lgG/+8DVs7jZdy0XDMwUAEcBmStw== X-Google-Smtp-Source: ABdhPJyl2ukrRTzp1IQJQVNIVqPRMmwk9WxqOoAjFGNEKSU/hBwHb3kqGSAVzPSDgJC7rAKV3s9odQ9+fjtCU0o5D74= X-Received: by 2002:a05:6808:602:: with SMTP id y2mr652138oih.11.1603995006006; Thu, 29 Oct 2020 11:10:06 -0700 (PDT) MIME-Version: 1.0 References: <20201028205101.47583-1-andriy.shevchenko@linux.intel.com> <20201028205101.47583-2-andriy.shevchenko@linux.intel.com> <20201029144656.GD4077@smile.fi.intel.com> In-Reply-To: From: Ricardo Ribalda Date: Thu, 29 Oct 2020 19:09:53 +0100 Message-ID: Subject: Re: [PATCH v1 2/3] Documentation: firmware-guide: gpio-properties: active_low only for GpioIo() To: Andy Shevchenko Cc: Andy Shevchenko , Mika Westerberg , ACPI Devel Maling List , "Rafael J. Wysocki" , "open list:GPIO SUBSYSTEM" , Tomasz Figa Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org (clicked on reply instead of reply all sorry) On Thu, Oct 29, 2020 at 6:32 PM Ricardo Ribalda wrote: > > Hi Andy > > On Thu, Oct 29, 2020 at 6:26 PM Andy Shevchenko > wrote: > > > > On Thu, Oct 29, 2020 at 7:20 PM Andy Shevchenko > > wrote: > > > > > > On Thu, Oct 29, 2020 at 7:17 PM Andy Shevchenko > > > wrote: > > > > On Thu, Oct 29, 2020 at 4:55 PM Ricardo Ribalda wrote: > > > > > On Thu, Oct 29, 2020 at 3:45 PM Andy Shevchenko > > > > > wrote: > > > > > > On Wed, Oct 28, 2020 at 10:10:42PM +0100, Ricardo Ribalda wrote: > > > > > > > > ... > > > > > > > > > > ActiveLevel field is described in 19.6.55 GpioInt (GPIO Interrupt Connection > > > > > > Resource Descriptor Macro). > > > > > > > > > > > > > Without using the active_low, how can we describe a pin that is > > > > > > > active low and has to trigger an irq on both edges? > > > > > > > > > > > > This is nonsense. > > > > > > What does it mean? > > > > > > > > > > Let me try to explain myself again: > > > > > > > > > > I have a gpio pin that produces IRQs on both edges. so ActiveLevel is Both > > > > > > > > > > The problem is that the value of that pin is inverted: Low means 1 and > > > > > high means 0. > > > > > > > > > > How can I describe that the pin "is inverted" without using the _DSD field? > > > > > > > > "Both edges" and "inverted" or "polarity low" in one sentence make no sense. > > > > > > To be on the constructive side, I can *imagine* so badly designed > > > hardware that uses level and edge at the same time, but before I go to > > > conclusions, can you share relevant (pieces of) datasheet? > > > > The [1] is a real example of how GPIO is being used to detect changing > > of current level of the signal. > > Note, ACPI tables for that device have problems [2], but I guess you > > may get the idea. > > > This is exactly what I need to do. Get an IRQ whenever the value > changes. But the pin is "inverted" > > This is the "schematic" : https://ibb.co/f8GMBbP . I want to pass to > userspace a "1" when the switch is closed and "0" when it is open. > And there are also other devices where the swith works the other way around, so the acpi should be verbose enough to describe both situations. With my proposal (use the same active_low field as with GpioIO) we cover both usecases. > > > > > > > > [1]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L138 > > [2]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L45 > > > > -- > > With Best Regards, > > Andy Shevchenko > > > > -- > Ricardo Ribalda -- Ricardo Ribalda