ath5k: fix SIFS time handling

ath5k uses 8 usec as a sifs time, extracted from the initvals, whereas the
standard requires a sifs time of 10. The difference originates from the fact
that the SIFS register has an offset of 2 usec.
Fix the SIFS time definition to use the standard value of 10 usec and subtract
2 usecs when writing the SIFS register.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 2 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath5k/ath5k.h b/drivers/net/wireless/ath/ath5k/ath5k.h
index 996d8afafdb7..a49aeac378cd 100644
--- a/drivers/net/wireless/ath/ath5k/ath5k.h
+++ b/drivers/net/wireless/ath/ath5k/ath5k.h
@@ -224,8 +224,7 @@
 
 /* SIFS */
 #define AR5K_INIT_SIFS_TURBO                    6
-/* XXX: 8 from initvals 10 from standard */
-#define AR5K_INIT_SIFS_DEFAULT_BG               8
+#define AR5K_INIT_SIFS_DEFAULT_BG               10
 #define AR5K_INIT_SIFS_DEFAULT_A                16
 #define AR5K_INIT_SIFS_HALF_RATE                32
 #define AR5K_INIT_SIFS_QUARTER_RATE             64
diff --git a/drivers/net/wireless/ath/ath5k/qcu.c b/drivers/net/wireless/ath/ath5k/qcu.c
index 93abcfacd990..b18c5021aac3 100644
--- a/drivers/net/wireless/ath/ath5k/qcu.c
+++ b/drivers/net/wireless/ath/ath5k/qcu.c
@@ -519,7 +519,7 @@ int ath5k_hw_set_ifs_intervals(struct ath5k_hw *ah, unsigned int slot_time)
                 return -EINVAL;
 
         sifs = ath5k_hw_get_default_sifs(ah);
-        sifs_clock = ath5k_hw_htoclock(ah, sifs);
+        sifs_clock = ath5k_hw_htoclock(ah, sifs - 2);
 
         /* EIFS
          * Txtime of ack at lowest rate + SIFS + DIFS