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