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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 00A5AECE58C for ; Fri, 11 Oct 2019 09:41:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C999C21D7C for ; Fri, 11 Oct 2019 09:41:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727646AbfJKJlU convert rfc822-to-8bit (ORCPT ); Fri, 11 Oct 2019 05:41:20 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:46846 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbfJKJlU (ORCPT ); Fri, 11 Oct 2019 05:41:20 -0400 Received: from 79.184.255.36.ipv4.supernova.orange.pl (79.184.255.36) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.292) id b8f52977fd553eb6; Fri, 11 Oct 2019 11:41:18 +0200 From: "Rafael J. Wysocki" To: Kacper =?utf-8?B?UGl3acWEc2tp?= Cc: rui.zhang@intel.com, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ACPI: acpi_video: update doc for acpi_video_bus_DOS Date: Fri, 11 Oct 2019 11:41:17 +0200 Message-ID: <3045273.zdn4mdtSDm@kreacher> In-Reply-To: <20191007154818.7416-1-cosiekvfj@o2.pl> References: <20191007154818.7416-1-cosiekvfj@o2.pl> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Monday, October 7, 2019 5:48:18 PM CEST Kacper Piwiński wrote: > commit: > efaa14c > > "Starting from win8, MS backlight control driver will set bit 2 of the > parameter of control method _DOS, to inform firmware it should not > perform any automatic brightness changes. This mostly affects hotkey > notification deliver - if we do not set this bit, on hotkey press, > firmware may choose to adjust brightness level instead of sending out > notification and doing nothing." > > win7: > https://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/BrightnessCtrl.docx > > "To avoid problems that might occur if both the system firmware and > the monitor driver control the brightness of the display, the display > miniport driver should set bit 2 of the argument to the _DOS method. > Setting this bit notifies the system firmware that it should not > perform any automatic display brightness changes. The WDDM > driver must set this particular bit because it controls the _DOS > method. The other bits in the _DOS method control the behavior of > the firmware in response to the display switch hot keys." > > win8: > http://read.pudn.com/downloads193/doc/907411/Brightness.doc > > Signed-off-by: Kacper Piwiński > --- > drivers/acpi/acpi_video.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c > index 4f325e47519f..2f380e7381d6 100644 > --- a/drivers/acpi/acpi_video.c > +++ b/drivers/acpi/acpi_video.c > @@ -699,9 +699,13 @@ acpi_video_device_EDID(struct acpi_video_device *device, > * event notify code. > * lcd_flag : > * 0. The system BIOS should automatically control the brightness level > - * of the LCD when the power changes from AC to DC > + * of the LCD when: > + * - the power changes from AC to DC (ACPI appendix B) > + * - a brightness hotkey gets pressed (implied by Win7/8 backlight docs) > * 1. The system BIOS should NOT automatically control the brightness > - * level of the LCD when the power changes from AC to DC. > + * level of the LCD when: > + * - the power changes from AC to DC (ACPI appendix B) > + * - a brightness hotkey gets pressed (implied by Win7/8 backlight docs) > * Return Value: > * -EINVAL wrong arg. > */ > Applying as 5.5 material, thanks!