ACPI: thinkpad-acpi: prefer standard ACPI backlight level control

[safe/jmp/linux-2.6] / drivers / misc / thinkpad_acpi.c

diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 56a21e6..109bd27 100644 (file)
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -3174,6 +3174,39 @@ static int __init brightness_check_levels(void)
        return (ACPI_SUCCESS(status) && found_node != NULL);
 }
 
+static acpi_status __init brightness_find_bcl(acpi_handle handle, u32 lvl,
+                                       void *context, void **rv)
+{
+       char name[ACPI_PATH_SEGMENT_LENGTH];
+       struct acpi_buffer buffer = { sizeof(name), &name };
+
+       if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer)) &&
+           !strncmp("_BCL", name, sizeof(name) - 1)) {
+               *rv = handle;
+               return AE_CTRL_TERMINATE;
+       } else {
+               return AE_OK;
+       }
+}
+
+static int __init brightness_check_std_acpi_support(void)
+{
+       int status;
+       void *found_node = NULL;
+
+       if (!vid_handle) {
+               IBM_ACPIHANDLE_INIT(vid);
+       }
+       if (!vid_handle)
+               return 0;
+
+       /* Search for a _BCL method, but don't execute it */
+       status = acpi_walk_namespace(ACPI_TYPE_METHOD, vid_handle, 3,
+                                    brightness_find_bcl, NULL, &found_node);
+
+       return (ACPI_SUCCESS(status) && found_node != NULL);
+}
+
 static int __init brightness_init(struct ibm_init_struct *iibm)
 {
        int b;
@@ -3186,6 +3219,12 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
                dbg_printk(TPACPI_DBG_INIT,
                           "brightness support disabled by module parameter\n");
                return 1;
+       } else if (brightness_enable > 1) {
+               if (brightness_check_std_acpi_support()) {
+                       printk(IBM_NOTICE
+                              "standard ACPI backlight interface available, not loading native one...\n");
+                       return 1;
+               }
        }
 
        if (!brightness_mode) {