From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhang Rui Subject: [PATCH] ACPI video: Still use ACPI backlight control if _DOS doesn't exist Date: Wed, 20 Jun 2012 09:48:43 +0800 Message-ID: <1340156923.1682.16.camel@rui.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com ([134.134.136.24]:60900 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750831Ab2FTBrG (ORCPT ); Tue, 19 Jun 2012 21:47:06 -0400 Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Len, Brown" Cc: "linux-acpi@vger.kernel.org" This is a regression introduced by commit ea9f8856bd6d4ed45885b06a338f7362cd6c60e5 https://bugzilla.kernel.org/show_bug.cgi?id=43168 Some platforms don't have _DOS control method, but the ACPI backlight still works. We should not invoke _DOS for these platforms. CC : Igor Murzov Signed-off-by: Zhang Rui --- drivers/acpi/video.c | 2 ++ 1 file changed, 2 insertions(+) Index: rtd3/drivers/acpi/video.c =================================================================== --- rtd3.orig/drivers/acpi/video.c +++ rtd3/drivers/acpi/video.c @@ -558,6 +558,8 @@ acpi_video_bus_DOS(struct acpi_video_bus union acpi_object arg0 = { ACPI_TYPE_INTEGER }; struct acpi_object_list args = { 1, &arg0 }; + if (!video->cap._DOS) + return 0; if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1) return -EINVAL;