From 99fd28e19429f5212f0758adc1b2f08c6e63b6db Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Tue, 22 Mar 2011 16:30:27 -0700
Subject: [PATCH] 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@redhat.com>
Acked-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Cc: Mourad De Clerck <mourad@aquazul.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/video/backlight/mbp_nvidia_bl.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/video/backlight/mbp_nvidia_bl.c b/drivers/video/backlight/mbp_nvidia_bl.c
index b22cfb24bd55..dd0e145170b7 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;