[3.16.y-ckt stable] Patch "ACPI / video: Load the module even if ACPI is disabled" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Thu Mar 19 10:13:21 UTC 2015

This is a note to let you know that I have just added a patch titled

    ACPI / video: Load the module even if ACPI is disabled

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:


This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see



>From 9491ccd652f3de5f7b1d966c939bdc2b191e3921 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris at chris-wilson.co.uk>
Date: Sun, 1 Mar 2015 10:41:37 +0000
Subject: ACPI / video: Load the module even if ACPI is disabled

commit 6e17cb12881ba8d5e456b89f072dc6b70048af36 upstream.

i915.ko depends upon the acpi/video.ko module and so refuses to load if
ACPI is disabled at runtime if for example the BIOS is broken beyond
repair. acpi/video provides an optional service for i915.ko and so we
should just allow the modules to load, but do no nothing in order to let
the machines boot correctly.

Reported-by: Bill Augur <bill-auger at programmer.net>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Jani Nikula <jani.nikula at intel.com>
Acked-by: Aaron Lu <aaron.lu at intel.com>
[ rjw: Fixed up the new comment in acpi_video_init() ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/acpi/video.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 0f9bf52792b5..095b94f6b9d8 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -2301,6 +2301,17 @@ EXPORT_SYMBOL(acpi_video_unregister_backlight);

 static int __init acpi_video_init(void)
+	/*
+	 * Let the module load even if ACPI is disabled (e.g. due to
+	 * a broken BIOS) so that i915.ko can still be loaded on such
+	 * old systems without an AcpiOpRegion.
+	 *
+	 * acpi_video_register() will report -ENODEV later as well due
+	 * to acpi_disabled when i915.ko tries to register itself afterwards.
+	 */
+	if (acpi_disabled)
+		return 0;

 	if (intel_opregion_present())

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