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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 D6D0BC55179 for ; Thu, 29 Oct 2020 14:45:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82AC620738 for ; Thu, 29 Oct 2020 14:45:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727705AbgJ2Op5 (ORCPT ); Thu, 29 Oct 2020 10:45:57 -0400 Received: from mga12.intel.com ([192.55.52.136]:26328 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726521AbgJ2Op4 (ORCPT ); Thu, 29 Oct 2020 10:45:56 -0400 IronPort-SDR: ehqlgiIgw+jVo3sNQsOQdPzNKw40dp9N3NZtnWPq1aFjAV9K1aQyEwRL2aMmEkjStfI3hzkhOi 1le7M3x33h9w== X-IronPort-AV: E=McAfee;i="6000,8403,9788"; a="147723965" X-IronPort-AV: E=Sophos;i="5.77,430,1596524400"; d="scan'208";a="147723965" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Oct 2020 07:45:56 -0700 IronPort-SDR: oZo9X9lcHoVODPC7Qf1h0zpJ2ps1bbmY/set4adm8ulRc9eH5rGtuaSJZyRsOu6+xZf5/6onLr wrBGZorOErvg== X-IronPort-AV: E=Sophos;i="5.77,430,1596524400"; d="scan'208";a="323725248" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Oct 2020 07:45:54 -0700 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kY9Ca-001Je5-As; Thu, 29 Oct 2020 16:46:56 +0200 Date: Thu, 29 Oct 2020 16:46:56 +0200 From: Andy Shevchenko To: Ricardo Ribalda Cc: Mika Westerberg , linux-acpi@vger.kernel.org, "Rafael J. Wysocki" , linux-gpio@vger.kernel.org Subject: Re: [PATCH v1 2/3] Documentation: firmware-guide: gpio-properties: active_low only for GpioIo() Message-ID: <20201029144656.GD4077@smile.fi.intel.com> References: <20201028205101.47583-1-andriy.shevchenko@linux.intel.com> <20201028205101.47583-2-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wed, Oct 28, 2020 at 10:10:42PM +0100, Ricardo Ribalda wrote: > Hi Andy > > Thanks for your patch and super fast response. > > I think there are two different concepts here: > > 1) when the pin has a low value, it is 0 or a 1? =>active_low I'm not sure I have got it. GpioIo() has no such property and _DSD active_low is documented as being polarity setting: active_low == 1 => active low polarity. > 2) when do I get an irq, low->high or high->low => irq polarity IRQ polarity is clearly defined by GpioInt() resource in the ACPI specification. > When I read the acpi spec for GpioInt() > https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf page > 934, it has the same problem as for GpioIo(), it does not express the > active_low and this is where the _DSD field comes handy. 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? -- With Best Regards, Andy Shevchenko