carl9170: fix noise dBm conversion

Ever since carl9170 gained support to read the noisefloor,
the reported noisefloor level was pretty poor.

Initially I assumed that something was wrong in the PHY
setup and it would be impossible to fix without any
guidances. But this was not the case. In fact the nf
readings were correct and the thing that was broken
was the "simple" sign extension code!

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/carl9170/phy.c b/drivers/net/wireless/ath/carl9170/phy.c
index fe265e3e6ac4846a4d422de0d2200372c0f6aa1e..7df8f711f5d8f4da337f720da8c3f4c449bd3f69 100644 (file)
--- a/drivers/net/wireless/ath/carl9170/phy.c
+++ b/drivers/net/wireless/ath/carl9170/phy.c
@@ -1558,9 +1558,9 @@ static int carl9170_set_power_cal(struct ar9170 *ar, u32 freq,
 static int carl9170_calc_noise_dbm(u32 raw_noise)
 {
        if (raw_noise & 0x100)
-               return ~((raw_noise & 0x0ff) >> 1);
+               return ~0x1ff | raw_noise;
        else
-               return (raw_noise & 0xff) >> 1;
+               return raw_noise;
 }
 
 int carl9170_get_noisefloor(struct ar9170 *ar)