From: Matthew Garrett <mjg@redhat.com>
Date: Tue, 3 Nov 2009 14:17:52 -0500
Subject: [acpi] thinkpad_acpi: disable ecnvram brightness on some
Message-id: 1257275872-15570-1-git-send-email-mjg@redhat.com
O-Subject: [PATCH] thinkpad_acpi: Disable ecnvram brightness control on Intel-based IBM machines
Bugzilla: 522745
RH-Acked-by: Stefan Assmann <sassmann@redhat.com>
RH-Acked-by: Danny Feng <dfeng@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>

Some Intel-based Thinkpads made by IBM need to use the nvram approach to
storing brightness, rather than the hybrid nvram/EC approach used by
default. This is a simplication of the upstream code in commit
59fe4fe34d7afdf63208124f313be9056feaa2f4 . Bugzilla #522745.

diff --git a/drivers/acpi/thinkpad_acpi.c b/drivers/acpi/thinkpad_acpi.c
index eba93c5..a1bf850 100644
--- a/drivers/acpi/thinkpad_acpi.c
+++ b/drivers/acpi/thinkpad_acpi.c
@@ -4310,6 +4310,20 @@ static int __init brightness_check_levels(void)
 	return (ACPI_SUCCESS(status) && found_node != NULL);
 }
 
+static int __init brightness_mode_quirk(void)
+{
+	switch (thinkpad_id.bios_model) {
+	case 0x5531:
+	case 0x5631:
+	case 0x5731:
+	case 0x3037:
+	case 0x3437:
+	case 0x3537:
+		return 1;
+	}
+	return 0;
+}
+
 static int __init brightness_init(struct ibm_init_struct *iibm)
 {
 	int b;
@@ -4328,8 +4342,12 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 	if (!brightness_mode) {
 		if (thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO)
 			brightness_mode = 2;
-		else
-			brightness_mode = 3;
+		else {
+			if (brightness_mode_quirk())
+				brightness_mode = 2;
+			else
+				brightness_mode = 3;
+		}
 
 		dbg_printk(TPACPI_DBG_INIT, "selected brightness_mode=%d\n",
 			brightness_mode);