linux-kernel - [PATCH 3.10 61/62] ACPI / video: Load the module even if ACPI is disabled

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Message-Id: <20150316140935.949227014@linuxfoundation.org>
Date:	Mon, 16 Mar 2015 15:10:18 +0100
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Bill Augur <bill-auger@...grammer.net>,
	Chris Wilson <chris@...is-wilson.co.uk>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jani Nikula <jani.nikula@...el.com>,
	Aaron Lu <aaron.lu@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.10 61/62] ACPI / video: Load the module even if ACPI is disabled

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Wilson <chris@...is-wilson.co.uk>

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@...grammer.net>
Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Jani Nikula <jani.nikula@...el.com>
Acked-by: Aaron Lu <aaron.lu@...el.com>
[ rjw: Fixed up the new comment in acpi_video_init() ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/acpi/video.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -1953,6 +1953,17 @@ EXPORT_SYMBOL(acpi_video_unregister);

 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;
+
 	dmi_check_system(video_dmi_table);

 	if (intel_opregion_present())

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