X-Git-Url: https://jxself.org/git/?a=blobdiff_plain;f=target_firmware%2Fwlan%2Fif_ath.c;h=bea411a58112ec4f5dd1906ea8a61f46f9a9d4ec;hb=24b5105e0730aaeffb8a7b0b6b0d93eec6190b86;hp=206b5c0e2c674d0a417f7db530791b130b19b2bb;hpb=583a029b620214fce590e7fbb960dbba290afe23;p=open-ath9k-htc-firmware.git

diff --git a/target_firmware/wlan/if_ath.c b/target_firmware/wlan/if_ath.c
index 206b5c0..bea411a 100755
--- a/target_firmware/wlan/if_ath.c
+++ b/target_firmware/wlan/if_ath.c
@@ -56,6 +56,8 @@
 #include "if_athvar.h"
 #include "ah_desc.h"
 #include "ah.h"
+#include "ratectrl.h"
+#include "ah_internal.h"
 
 static a_int32_t ath_numrxbufs = -1;
 static a_int32_t ath_numrxdescs = -1;
@@ -82,19 +84,36 @@ void ath_tgt_tx_sched_normal(struct ath_softc_tgt *sc, struct ath_buf *bf);
 void ath_tgt_tx_sched_nonaggr(struct ath_softc_tgt *sc,struct ath_buf * bf_host);
 
 /*
- * Extend a 32 bit TSF to 64 bit, taking wrapping into account.
+ * Extend a 32 bit TSF to nearest 64 bit TSF value.
+ * When the adapter is a STATION, its local TSF is periodically modified by
+ * the hardware to match the BSS TSF (as received in beacon packets), and
+ * rstamp may appear to be from the future or from the past (with reference
+ * to the current local TSF) because of jitter. This is mostly noticable in
+ * highly congested channels. The code uses signed modulo arithmetic to
+ * handle both past/future cases and signed-extension to avoid branches.
+ * Test cases:
+ * extend(0x0000001200000004, 0x00000006) == 0x0000001200000006
+ * extend(0x0000001200000004, 0x00000002) == 0x0000001200000002
+ * extend(0x0000001200000004, 0xfffffffe) == 0x00000011fffffffe  ! tsfhigh--
+ * extend(0x000000127ffffffe, 0x80000002) == 0x0000001280000002
+ * extend(0x0000001280000002, 0x7ffffffe) == 0x000000127ffffffe
+ * extend(0x00000012fffffffc, 0xfffffffe) == 0x00000012fffffffe
+ * extend(0x00000012fffffffc, 0xfffffffa) == 0x00000012fffffffa
+ * extend(0x00000012fffffffc, 0x00000002) == 0x0000001300000002  ! tsfhigh++
  */
 static u_int64_t ath_extend_tsf(struct ath_softc_tgt *sc, u_int32_t rstamp)
 {
 	struct ath_hal *ah = sc->sc_ah;
 	u_int64_t tsf;
+	u_int32_t tsf_low;
+	a_int64_t tsf_delta;  /* signed int64 */
 
 	tsf = ah->ah_getTsf64(ah);
+	tsf_low = tsf & 0xffffffffUL;
 
-	if (rstamp > (tsf & 0xffffffffULL))
-		tsf -= 0x100000000ULL;
+	tsf_delta = (a_int32_t)((rstamp - tsf_low) & 0xffffffffUL);
 
-	return ((tsf & ~0xffffffffULL) | rstamp);
+	return (tsf + (u_int64_t)tsf_delta);
 }
 
 static a_int32_t ath_rate_setup(struct ath_softc_tgt *sc, a_uint32_t mode)