From: Alex Murray <murray.alex at gmail.com>
The light sensors ALV0 and ALV1 on newer MacBooks (early 2008 and
later) changed to report 10 bytes instead the earlier 6, and the
sensor encoding subsequently changed. As a result, the reported light
sensors readings are much too low.
>From experiments leading up to this patch, it seems only the ALV0 is
reporting data, and the most useful value therein is a 10-bit
big-endian value at offset 6. This suggests that a new protocol was
added as a backward-compatible replacement on top of the old one.
This patch makes applesmc report the improved light sensor reading for
the new machines, on a scale in conformance with earlier ones.
Signed-off-by: Alex Murray <murray.alex at gmail.com>
Signed-off-by: Henrik Rydberg <rydberg at euromail.se>
---
drivers/hwmon/applesmc.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index dca47a5..e301862 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -590,6 +590,11 @@ static ssize_t applesmc_light_show(struct device *dev,
}
ret = applesmc_read_key(LIGHT_SENSOR_LEFT_KEY, buffer, data_length);
+ /* newer macbooks report a single 10-bit bigendian value */
+ if (data_length == 10) {
+ left = be16_to_cpu(*(__be16 *)(buffer + 6)) >> 2;
+ goto out;
+ }
left = buffer[2];
if (ret)
goto out;
--
1.5.6.3
