thinkpad-acpi: fix incorrect use of TPACPI_BRGHT_MODE_ECNVRAM

HBRV-based default selection of backlight control strategy didn't work
well, at least the X41 defines it but doesn't use it and I don't think
it will stop there.

Switch to a white/blacklist.  All models that have HBRV defined have
been included in the list, and initially all ATI GPUs will get
ECNVRAM, and the Intel GPUs will get UCMS_STEP.

Symptoms of incorrect backlight mode selection are:

1. Non-working backlight control through sysfs;

2. Backlight gets reset to the lowest level at every shutdown, reboot
   and when thinkpad-acpi gets unloaded;

This fixes a regression in 2.6.30, bugzilla #13826

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Reported-by: Tobias Diedrich <ranma+kernel@tdiedrich.de>
Cc: stable@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 18f9ee6..e856008 100644 (file)
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -5642,14 +5642,48 @@ static struct backlight_ops ibm_backlight_data = {
 
 /* --------------------------------------------------------------------- */
 
+/*
+ * These are only useful for models that have only one possibility
+ * of GPU.  If the BIOS model handles both ATI and Intel, don't use
+ * these quirks.
+ */
+#define TPACPI_BRGHT_Q_NOEC    0x0001  /* Must NOT use EC HBRV */
+#define TPACPI_BRGHT_Q_EC      0x0002  /* Should or must use EC HBRV */
+#define TPACPI_BRGHT_Q_ASK     0x8000  /* Ask for user report */
+
+static const struct tpacpi_quirk brightness_quirk_table[] __initconst = {
+       /* Models with ATI GPUs known to require ECNVRAM mode */
+       TPACPI_Q_IBM('1', 'Y', TPACPI_BRGHT_Q_EC),      /* T43/p ATI */
+
+       /* Models with ATI GPUs (waiting confirmation) */
+       TPACPI_Q_IBM('1', 'R', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
+       TPACPI_Q_IBM('1', 'Q', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
+       TPACPI_Q_IBM('7', '6', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
+       TPACPI_Q_IBM('7', '8', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_EC),
+
+       /* Models with Intel Extreme Graphics 2 (waiting confirmation) */
+       TPACPI_Q_IBM('1', 'V', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_NOEC),
+       TPACPI_Q_IBM('1', 'W', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_NOEC),
+       TPACPI_Q_IBM('1', 'U', TPACPI_BRGHT_Q_ASK|TPACPI_BRGHT_Q_NOEC),
+
+       /* Models with Intel GMA900 */
+       TPACPI_Q_IBM('7', '0', TPACPI_BRGHT_Q_NOEC),    /* T43, R52 */
+       TPACPI_Q_IBM('7', '4', TPACPI_BRGHT_Q_NOEC),    /* X41 */
+       TPACPI_Q_IBM('7', '5', TPACPI_BRGHT_Q_NOEC),    /* X41 Tablet */
+};
+
 static int __init brightness_init(struct ibm_init_struct *iibm)
 {
        int b;
+       unsigned long quirks;
 
        vdbg_printk(TPACPI_DBG_INIT, "initializing brightness subdriver\n");
 
        mutex_init(&brightness_mutex);
 
+       quirks = tpacpi_check_quirks(brightness_quirk_table,
+                               ARRAY_SIZE(brightness_quirk_table));
+
        /*
         * We always attempt to detect acpi support, so as to switch
         * Lenovo Vista BIOS to ACPI brightness mode even if we are not
@@ -5706,23 +5740,13 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
        /* TPACPI_BRGHT_MODE_AUTO not implemented yet, just use default */
        if (brightness_mode == TPACPI_BRGHT_MODE_AUTO ||
            brightness_mode == TPACPI_BRGHT_MODE_MAX) {
-               if (thinkpad_id.vendor == PCI_VENDOR_ID_IBM) {
-                       /*
-                        * IBM models that define HBRV probably have
-                        * EC-based backlight level control
-                        */
-                       if (acpi_evalf(ec_handle, NULL, "HBRV", "qd"))
-                               /* T40-T43, R50-R52, R50e, R51e, X31-X41 */
-                               brightness_mode = TPACPI_BRGHT_MODE_ECNVRAM;
-                       else
-                               /* all other IBM ThinkPads */
-                               brightness_mode = TPACPI_BRGHT_MODE_UCMS_STEP;
-               } else
-                       /* All Lenovo ThinkPads */
+               if (quirks & TPACPI_BRGHT_Q_EC)
+                       brightness_mode = TPACPI_BRGHT_MODE_ECNVRAM;
+               else
                        brightness_mode = TPACPI_BRGHT_MODE_UCMS_STEP;
 
                dbg_printk(TPACPI_DBG_BRGHT,
-                          "selected brightness_mode=%d\n",
+                          "driver auto-selected brightness_mode=%d\n",
                           brightness_mode);
        }
 
@@ -5749,6 +5773,15 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
        vdbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_BRGHT,
                        "brightness is supported\n");
 
+       if (quirks & TPACPI_BRGHT_Q_ASK) {
+               printk(TPACPI_NOTICE
+                       "brightness: will use unverified default: "
+                       "brightness_mode=%d\n", brightness_mode);
+               printk(TPACPI_NOTICE
+                       "brightness: please report to %s whether it works well "
+                       "or not on your ThinkPad\n", TPACPI_MAIL);
+       }
+
        ibm_backlight_device->props.max_brightness =
                                (tp_features.bright_16levels)? 15 : 7;
        ibm_backlight_device->props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;