From 22c13f9d8179f4c9caecfcb60a95214562b9addc Mon Sep 17 00:00:00 2001
From: Thomas Renninger <trenn@suse.de>
Date: Fri, 1 Aug 2008 17:37:54 +0200
Subject: ACPI: video: Ignore devices that aren't present in hardware

This is a reimplemention of commit
0119509c4fbc9adcef1472817fda295334612976
from Matthew Garrett <mjg59@srcf.ucam.org>

This patch got removed because of a regression: ThinkPads with a
Intel graphics card and an Integrated Graphics Device BIOS implementation
stopped working.
In fact, they only worked because the ACPI device of the discrete, the
wrong one, got used (via int10). So ACPI functions were poking on the wrong
hardware used which is a sever bug.
The next patch provides support for above ThinkPads to be able to
switch brightness via the legacy thinkpad_acpi driver and automatically
detect when to use it.

Original commit message from Matthew Garrett:
    Vendors often ship machines with a choice of integrated or discrete
    graphics, and use the same DSDT for both. As a result, the ACPI video
    module will locate devices that may not exist on this specific platform.
    Attempt to determine whether the device exists or not, and abort the
    device creation if it doesn't.

http://bugzilla.kernel.org/show_bug.cgi?id=9614

Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
 drivers/acpi/video.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'drivers/acpi/video.c')

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index a29b0ccac65..6597c2a37c3 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -842,11 +842,16 @@ static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
 static int acpi_video_bus_check(struct acpi_video_bus *video)
 {
 	acpi_status status = -ENOENT;
-
+	struct device *dev;
 
 	if (!video)
 		return -EINVAL;
 
+	dev = acpi_get_physical_pci_device(video->device->handle);
+	if (!dev)
+		return -ENODEV;
+	put_device(dev);
+
 	/* Since there is no HID, CID and so on for VGA driver, we have
 	 * to check well known required nodes.
 	 */
-- 
cgit v1.2.3-70-g09d2