Hi,
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.
See also: http://bugzilla.kernel.org/show_bug.cgi?id=8375
Danny
From: Danny Kukawka <[email protected]>
Subject: ACPI video: Don't export sysfs backlight interface if query _BLC fail
if qeuery _BCL fail (e.g. because the method is missing in BIOS) don't
export the backlight interface to sysfs.
Signed-off-by: Danny Kukawka <[email protected]>
---
video.c | 78 ++++++++++++++++++++++++++++--------------------------
1 file changed, 41 insertions(+), 37 deletions(-)
--- linux-2.6.21/drivers/acpi/video.c 2007-04-26 13:50:51.000000000 +0200
+++ linux-2.6.21/drivers/acpi/video.c 2007-04-26 13:50:53.000000000 +0200
@@ -531,7 +531,6 @@
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;
@@ -565,50 +564,55 @@
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) {
- int count = 0;
- union acpi_object *o;
-
- br = kzalloc(sizeof(*br), GFP_KERNEL);
- if (!br) {
- printk(KERN_ERR "can't allocate memory\n");
- } else {
- br->levels = kmalloc(obj->package.count *
- sizeof *(br->levels), GFP_KERNEL);
- if (!br->levels)
- goto out;
-
- for (i = 0; i < obj->package.count; i++) {
- o = (union acpi_object *)&obj->package.
- elements[i];
- if (o->type != ACPI_TYPE_INTEGER) {
- printk(KERN_ERR PREFIX "Invalid data\n");
- continue;
- }
- br->levels[count] = (u32) o->integer.value;
- if (br->levels[count] > max_level)
- max_level = br->levels[count];
- count++;
- }
- out:
- if (count < 2) {
- kfree(br->levels);
- kfree(br);
+ if (obj->package.count >= 2) {
+ int count = 0;
+ union acpi_object *o;
+
+ br = kzalloc(sizeof(*br), GFP_KERNEL);
+ if (!br) {
+ printk(KERN_ERR "can't allocate memory\n");
} else {
- br->count = count;
- device->brightness = br;
- ACPI_DEBUG_PRINT((ACPI_DB_INFO,
- "found %d brightness levels\n",
- count));
+ br->levels = kmalloc(obj->package.count *
+ sizeof *(br->levels), GFP_KERNEL);
+ if (!br->levels)
+ goto out;
+
+ for (i = 0; i < obj->package.count; i++) {
+ o = (union acpi_object *)&obj->package.
+ elements[i];
+ if (o->type != ACPI_TYPE_INTEGER) {
+ printk(KERN_ERR PREFIX "Invalid data\n");
+ continue;
+ }
+ br->levels[count] = (u32) o->integer.value;
+
+ if (br->levels[count] > max_level)
+ max_level = br->levels[count];
+ count++;
+ }
+ out:
+ if (count < 2) {
+ kfree(br->levels);
+ kfree(br);
+ } else {
+ br->count = count;
+ device->brightness = br;
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "found %d brightness levels\n",
+ count));
+ }
}
}
+
+ } 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;
-
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