ACPI: thinkpad-acpi: support 16 levels of brightness (v3)

Lenovo ThinkPads often have 16 brightness levels in EC, and not just eight
levels like older ThinkPads.  They also have standard ACPI backlight
brightness control.

We detect the number of brightness levels by the presence of a BCLL package
with 16 entries.  If BCLL is not there, we assume eight levels (Z6*).  If
it is there, but it doesn't have 16 entries, we assume eight levels (T60).
Otherwise we assume sixteen levels (T61, X61, etc).

We don't use _BCL because it can have side-effects in thinkpads.  Thanks to
Thomas Renninger <trenn@suse.de> for notifying me of this potential
problem.

Using the standard ACPI backlight brightness control *instead* of the
native thinkpad backlight control is a better idea, though.  A different
patch will take care of this.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index 3abcc8120634..8ca19c333727 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -84,7 +84,7 @@
 
 /* ThinkPad CMOS NVRAM constants */
 #define TP_NVRAM_ADDR_BRIGHTNESS       0x5e
-#define TP_NVRAM_MASK_LEVEL_BRIGHTNESS 0x07
+#define TP_NVRAM_MASK_LEVEL_BRIGHTNESS 0x0f
 #define TP_NVRAM_POS_LEVEL_BRIGHTNESS 0
 
 #define onoff(status,bit) ((status) & (1 << (bit)) ? "on" : "off")
@@ -246,6 +246,7 @@ static struct {
         u32 hotkey_wlsw:1;
         u32 light:1;
         u32 light_status:1;
+        u32 bright_16levels:1;
         u32 wan:1;
         u32 fan_ctrl_status_undef:1;
         u32 input_device_registered:1;