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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 4E66DC433E1 for ; Thu, 27 Aug 2020 13:30:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AFAA22BF5 for ; Thu, 27 Aug 2020 13:30:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728204AbgH0N3p (ORCPT ); Thu, 27 Aug 2020 09:29:45 -0400 Received: from mga09.intel.com ([134.134.136.24]:25597 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728035AbgH0N22 (ORCPT ); Thu, 27 Aug 2020 09:28:28 -0400 IronPort-SDR: zA+9aKbt4jHDA2Gj7+B6a7P9oPa3Y3I5+2nlIuGa/BIjYnX4khduS2wUBX8Q4KWpsOKR0V9McP xadUjzfQNhMA== X-IronPort-AV: E=McAfee;i="6000,8403,9725"; a="157503047" X-IronPort-AV: E=Sophos;i="5.76,359,1592895600"; d="scan'208";a="157503047" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2020 06:28:28 -0700 IronPort-SDR: ROXbn60uGAEfxQlLWOlgDCyR5qTaP+nvWHDUAHFNKYScuFTf6y15VebIoX9/cDXydcihspvv+D 5o1jDewAc/sg== X-IronPort-AV: E=Sophos;i="5.76,359,1592895600"; d="scan'208";a="295723842" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Aug 2020 06:28:24 -0700 Received: by paasikivi.fi.intel.com (Postfix, from userid 1000) id 3DD3B20722; Thu, 27 Aug 2020 16:28:22 +0300 (EEST) Date: Thu, 27 Aug 2020 16:28:22 +0300 From: Sakari Ailus To: Randy Dunlap Cc: linux-i2c@vger.kernel.org, Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Bingbu Cao , linux-media@vger.kernel.org, Chiranjeevi Rapolu , Hyungwoo Yang , Bartosz Golaszewski , Arnd Bergmann , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , rajmohan.mani@intel.com, Tomasz Figa , "Qiu, Tian Shu" Subject: Re: [PATCH v6 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property Message-ID: <20200827132822.GI24582@paasikivi.fi.intel.com> References: <20200826115432.6103-1-sakari.ailus@linux.intel.com> <20200826115432.6103-7-sakari.ailus@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Wed, Aug 26, 2020 at 11:06:22AM -0700, Randy Dunlap wrote: > On 8/26/20 4:54 AM, Sakari Ailus wrote: > > Document the probe-low-power _DSD property and how it is used with I²C > > drivers. > > > > Signed-off-by: Sakari Ailus > > --- > > .../acpi/dsd/allow-low-power-probe.rst | 28 +++++++++++++++++++ > > Documentation/firmware-guide/acpi/index.rst | 1 + > > 2 files changed, 29 insertions(+) > > create mode 100644 Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > > > diff --git a/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > new file mode 100644 > > index 0000000000000..6fcc89162b898 > > --- /dev/null > > +++ b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > @@ -0,0 +1,28 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +====================================== > > +Probing I²C devices in low power state > > +====================================== > > + > > +Introduction > > +============ > > + > > +In some cases it may be preferred to leave certain devices powered off for the > > +entire system bootup if powering on these devices has adverse side effects, > > +beyond just powering on the said device. Linux recognizes the _DSD property > > +"allow-low-power-probe" that can be used for this purpose. > > + > > +How it works > > +============ > > + > > +The property "allow-low-power-probe" boolean property may be used to tell Linux > > Drop the first "property". > Thanks, will fix for v7. > > +that the I²C framework should instruct the kernel ACPI framework to leave the > > +device in the low power state. If the driver indicates its support for this by > > +setting the I2C_DRV_FL_ALLOW_LOW_POWER_PROBE flag in struct i2c_driver.flags This is leftover from v5 actually, I'll change the documentation to mention the allow_low_power_probe as well. > > +field and the "allow-low-power-probe" property is present, the device will not > > +be powered on for probe. > -- Kind regards, Sakari Ailus