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ACPI video: Don't export sysfs backlight interface if query _BCL fail

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Currently the acpi video module export the backlight interface to sysfs
also if acpi_video_device_lcd_query_levels() fails to read _BLC method
(e.g.  because the method is not available).  In this case the userspace
don't know which brightness level are supported and can't set a brightness
level (echo return with: "write error: Invalid Argument").  This happend
e.g.  on a ASUS RF1 (correct supported by the asus-laptop module).

The video module should not export the backlight interface if query _BLC fail,
because you can't set anything from userspace and this make it useless.

http://bugzilla.kernel.org/show_bug.cgi?id=8375

Signed-off-by: Danny Kukawka <dkukawka@suse.de>
Acked-by: Luming Yu <luming.yu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Danny Kukawka 2007-07-03 01:33:53 -04:00 committed by Len Brown
parent 23b0f015bf
commit f70ac0e965
1 changed files with 40 additions and 36 deletions
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12
drivers/acpi/video.c
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@ -559,7 +559,6 @@ acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
static void acpi_video_device_find_cap(struct acpi_video_device *device)
{
acpi_integer status;
acpi_handle h_dummy1;
int i;
u32 max_level = 0;
@ -593,9 +592,9 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
device->cap._DSS = 1;
}
status = acpi_video_device_lcd_query_levels(device, &obj);
if (ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
if (obj && obj->type == ACPI_TYPE_PACKAGE && obj->package.count >= 2) {
if (obj->package.count >= 2) {
int count = 0;
union acpi_object *o;
@ -616,6 +615,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
continue;
}
br->levels[count] = (u32) o->integer.value;
if (br->levels[count] > max_level)
max_level = br->levels[count];
count++;
@ -634,9 +634,13 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
}
}
} else {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available LCD brightness level\n"));
}
kfree(obj);
if (device->cap._BCL && device->cap._BCM && device->cap._BQC){
if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){
unsigned long tmp;
static int count = 0;
char *name;