ath9k: Add a few comments about mibevents

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/net/wireless/ath9k/hw.c b/drivers/net/wireless/ath9k/hw.c
index 0251e59f2f84..272c75816609 100644
--- a/drivers/net/wireless/ath9k/hw.c
+++ b/drivers/net/wireless/ath9k/hw.c
@@ -2526,6 +2526,11 @@ static void ath9k_ani_reset(struct ath_hal *ah)
         }
 }
 
+/*
+ * Process a MIB interrupt.  We may potentially be invoked because
+ * any of the MIB counters overflow/trigger so don't assume we're
+ * here because a PHY error counter triggered.
+ */
 void ath9k_hw_procmibevent(struct ath_hal *ah,
                            const struct ath9k_node_stats *stats)
 {
@@ -2533,18 +2538,20 @@ void ath9k_hw_procmibevent(struct ath_hal *ah,
         u32 phyCnt1, phyCnt2;
 
         DPRINTF(ah->ah_sc, ATH_DBG_ANI, "Processing Mib Intr\n");
-
+        /* Reset these counters regardless */
         REG_WRITE(ah, AR_FILT_OFDM, 0);
         REG_WRITE(ah, AR_FILT_CCK, 0);
         if (!(REG_READ(ah, AR_SLP_MIB_CTRL) & AR_SLP_MIB_PENDING))
                 REG_WRITE(ah, AR_SLP_MIB_CTRL, AR_SLP_MIB_CLEAR);
 
+        /* Clear the mib counters and save them in the stats */
         ath9k_hw_update_mibstats(ah, &ahp->ah_mibStats);
         ahp->ah_stats.ast_nodestats = *stats;
 
         if (!DO_ANI(ah))
                 return;
 
+        /* NB: these are not reset-on-read */
         phyCnt1 = REG_READ(ah, AR_PHY_ERR_1);
         phyCnt2 = REG_READ(ah, AR_PHY_ERR_2);
         if (((phyCnt1 & AR_MIBCNT_INTRMASK) == AR_MIBCNT_INTRMASK) ||
@@ -2552,6 +2559,7 @@ void ath9k_hw_procmibevent(struct ath_hal *ah,
                 struct ar5416AniState *aniState = ahp->ah_curani;
                 u32 ofdmPhyErrCnt, cckPhyErrCnt;
 
+                /* NB: only use ast_ani_*errs with AH_PRIVATE_DIAG */
                 ofdmPhyErrCnt = phyCnt1 - aniState->ofdmPhyErrBase;
                 ahp->ah_stats.ast_ani_ofdmerrs +=
                         ofdmPhyErrCnt - aniState->ofdmPhyErrCount;
@@ -2562,11 +2570,17 @@ void ath9k_hw_procmibevent(struct ath_hal *ah,
                         cckPhyErrCnt - aniState->cckPhyErrCount;
                 aniState->cckPhyErrCount = cckPhyErrCnt;
 
+                /*
+                 * NB: figure out which counter triggered.  If both
+                 * trigger we'll only deal with one as the processing
+                 * clobbers the error counter so the trigger threshold
+                 * check will never be true.
+                 */
                 if (aniState->ofdmPhyErrCount > aniState->ofdmTrigHigh)
                         ath9k_hw_ani_ofdm_err_trigger(ah);
                 if (aniState->cckPhyErrCount > aniState->cckTrigHigh)
                         ath9k_hw_ani_cck_err_trigger(ah);
-
+                /* NB: always restart to insure the h/w counters are reset */
                 ath9k_ani_restart(ah);
         }
 }