linux-kernel - [PATCH 2/3] mbp_nvidia_bl: Check that the backlight control functions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 16 Dec 2010 10:13:49 -0500
From:	Matthew Garrett <mjg@...hat.com>
To:	rpurdie@...ys.net
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Matthew Garrett <mjg@...hat.com>
Subject: [PATCH 2/3] mbp_nvidia_bl: Check that the backlight control functions

The SMI-based backlight control functionality may fail to work if the
system is running under EFI rather than BIOS. Check that the hardware
responds as expected, and exit if it doesn't.

Signed-off-by: Matthew Garrett <mjg@...hat.com>
---
 drivers/video/backlight/mbp_nvidia_bl.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/video/backlight/mbp_nvidia_bl.c b/drivers/video/backlight/mbp_nvidia_bl.c
index 984699b..11f6c47 100644
--- a/drivers/video/backlight/mbp_nvidia_bl.c
+++ b/drivers/video/backlight/mbp_nvidia_bl.c
@@ -143,6 +143,7 @@ static int __devinit mb_bl_add(struct acpi_device *dev)
 {
 	struct backlight_properties props;
 	struct pci_dev *host;
+	int intensity;
 
 	host = pci_get_bus_and_slot(0, 0);
 
@@ -163,6 +164,18 @@ static int __devinit mb_bl_add(struct acpi_device *dev)
 		return -ENODEV;
 	}
 
+	/* Check that the hardware responds - this may not work under EFI */
+
+	intensity = hw_data->backlight_ops.get_brightness(NULL);
+
+	if (!intensity) {
+		hw_data->set_brightness(1);
+		if (!hw_data->backlight_ops.get_brightness(NULL))
+			return -ENODEV;
+
+		hw_data->set_brightness(0);
+	}
+
 	if (!request_region(hw_data->iostart, hw_data->iolen,
 			    "Macbook backlight"))
 		return -ENXIO;
-- 
1.7.3.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/