ath9k_hw: optimize tx status descriptor processing

Disassembly shows, that at least on MIPS, the compiler generates a lot of
memory accesses to the same location in the descriptor field parsing.
Since it is operating on uncached memory, this can be quite expensive in
this hot path.
Change the code a bit to help the compiler optimize it properly, and get
rid of some unused fields in the ath_tx_status struct.

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

diff --git a/drivers/net/wireless/ath/ath9k/ar9002_mac.c b/drivers/net/wireless/ath/ath9k/ar9002_mac.c
index f5ed73dac2547fb71c9228e401f0dc9cb78095ef..3b4c52c9181c15958358f2097ac9396c2cec7dd9 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ar9002_mac.c
+++ b/drivers/net/wireless/ath/ath9k/ar9002_mac.c
@@ -208,77 +208,68 @@ static int ar9002_hw_proc_txdesc(struct ath_hw *ah, void *ds,
                                 struct ath_tx_status *ts)
 {
        struct ar5416_desc *ads = AR5416DESC(ds);
+       u32 status;
 
-       if ((ads->ds_txstatus9 & AR_TxDone) == 0)
+       status = ACCESS_ONCE(ads->ds_txstatus9);
+       if ((status & AR_TxDone) == 0)
                return -EINPROGRESS;
 
-       ts->ts_seqnum = MS(ads->ds_txstatus9, AR_SeqNum);
        ts->ts_tstamp = ads->AR_SendTimestamp;
        ts->ts_status = 0;
        ts->ts_flags = 0;
 
-       if (ads->ds_txstatus1 & AR_FrmXmitOK)
+       if (status & AR_TxOpExceeded)
+               ts->ts_status |= ATH9K_TXERR_XTXOP;
+       ts->tid = MS(status, AR_TxTid);
+       ts->ts_rateindex = MS(status, AR_FinalTxIdx);
+       ts->ts_seqnum = MS(status, AR_SeqNum);
+
+       status = ACCESS_ONCE(ads->ds_txstatus0);
+       ts->ts_rssi_ctl0 = MS(status, AR_TxRSSIAnt00);
+       ts->ts_rssi_ctl1 = MS(status, AR_TxRSSIAnt01);
+       ts->ts_rssi_ctl2 = MS(status, AR_TxRSSIAnt02);
+       if (status & AR_TxBaStatus) {
+               ts->ts_flags |= ATH9K_TX_BA;
+               ts->ba_low = ads->AR_BaBitmapLow;
+               ts->ba_high = ads->AR_BaBitmapHigh;
+       }
+
+       status = ACCESS_ONCE(ads->ds_txstatus1);
+       if (status & AR_FrmXmitOK)
                ts->ts_status |= ATH9K_TX_ACKED;
-       if (ads->ds_txstatus1 & AR_ExcessiveRetries)
+       if (status & AR_ExcessiveRetries)
                ts->ts_status |= ATH9K_TXERR_XRETRY;
-       if (ads->ds_txstatus1 & AR_Filtered)
+       if (status & AR_Filtered)
                ts->ts_status |= ATH9K_TXERR_FILT;
-       if (ads->ds_txstatus1 & AR_FIFOUnderrun) {
+       if (status & AR_FIFOUnderrun) {
                ts->ts_status |= ATH9K_TXERR_FIFO;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->ds_txstatus9 & AR_TxOpExceeded)
-               ts->ts_status |= ATH9K_TXERR_XTXOP;
-       if (ads->ds_txstatus1 & AR_TxTimerExpired)
+       if (status & AR_TxTimerExpired)
                ts->ts_status |= ATH9K_TXERR_TIMER_EXPIRED;
-
-       if (ads->ds_txstatus1 & AR_DescCfgErr)
+       if (status & AR_DescCfgErr)
                ts->ts_flags |= ATH9K_TX_DESC_CFG_ERR;
-       if (ads->ds_txstatus1 & AR_TxDataUnderrun) {
+       if (status & AR_TxDataUnderrun) {
                ts->ts_flags |= ATH9K_TX_DATA_UNDERRUN;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->ds_txstatus1 & AR_TxDelimUnderrun) {
+       if (status & AR_TxDelimUnderrun) {
                ts->ts_flags |= ATH9K_TX_DELIM_UNDERRUN;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->ds_txstatus0 & AR_TxBaStatus) {
-               ts->ts_flags |= ATH9K_TX_BA;
-               ts->ba_low = ads->AR_BaBitmapLow;
-               ts->ba_high = ads->AR_BaBitmapHigh;
-       }
+       ts->ts_shortretry = MS(status, AR_RTSFailCnt);
+       ts->ts_longretry = MS(status, AR_DataFailCnt);
+       ts->ts_virtcol = MS(status, AR_VirtRetryCnt);
 
-       ts->ts_rateindex = MS(ads->ds_txstatus9, AR_FinalTxIdx);
-       switch (ts->ts_rateindex) {
-       case 0:
-               ts->ts_ratecode = MS(ads->ds_ctl3, AR_XmitRate0);
-               break;
-       case 1:
-               ts->ts_ratecode = MS(ads->ds_ctl3, AR_XmitRate1);
-               break;
-       case 2:
-               ts->ts_ratecode = MS(ads->ds_ctl3, AR_XmitRate2);
-               break;
-       case 3:
-               ts->ts_ratecode = MS(ads->ds_ctl3, AR_XmitRate3);
-               break;
-       }
+       status = ACCESS_ONCE(ads->ds_txstatus5);
+       ts->ts_rssi = MS(status, AR_TxRSSICombined);
+       ts->ts_rssi_ext0 = MS(status, AR_TxRSSIAnt10);
+       ts->ts_rssi_ext1 = MS(status, AR_TxRSSIAnt11);
+       ts->ts_rssi_ext2 = MS(status, AR_TxRSSIAnt12);
 
-       ts->ts_rssi = MS(ads->ds_txstatus5, AR_TxRSSICombined);
-       ts->ts_rssi_ctl0 = MS(ads->ds_txstatus0, AR_TxRSSIAnt00);
-       ts->ts_rssi_ctl1 = MS(ads->ds_txstatus0, AR_TxRSSIAnt01);
-       ts->ts_rssi_ctl2 = MS(ads->ds_txstatus0, AR_TxRSSIAnt02);
-       ts->ts_rssi_ext0 = MS(ads->ds_txstatus5, AR_TxRSSIAnt10);
-       ts->ts_rssi_ext1 = MS(ads->ds_txstatus5, AR_TxRSSIAnt11);
-       ts->ts_rssi_ext2 = MS(ads->ds_txstatus5, AR_TxRSSIAnt12);
        ts->evm0 = ads->AR_TxEVM0;
        ts->evm1 = ads->AR_TxEVM1;
        ts->evm2 = ads->AR_TxEVM2;
-       ts->ts_shortretry = MS(ads->ds_txstatus1, AR_RTSFailCnt);
-       ts->ts_longretry = MS(ads->ds_txstatus1, AR_DataFailCnt);
-       ts->ts_virtcol = MS(ads->ds_txstatus1, AR_VirtRetryCnt);
-       ts->tid = MS(ads->ds_txstatus9, AR_TxTid);
-       ts->ts_antenna = 0;
 
        return 0;
 }

diff --git a/drivers/net/wireless/ath/ath9k/ar9003_mac.c b/drivers/net/wireless/ath/ath9k/ar9003_mac.c
index 3b424ca1ba844855b798e757e0d0727dd29e9e27..10c812e353a63b0294dab5669ab3888536eff0be 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ar9003_mac.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_mac.c
@@ -237,10 +237,12 @@ static int ar9003_hw_proc_txdesc(struct ath_hw *ah, void *ds,
                                 struct ath_tx_status *ts)
 {
        struct ar9003_txs *ads;
+       u32 status;
 
        ads = &ah->ts_ring[ah->ts_tail];
 
-       if ((ads->status8 & AR_TxDone) == 0)
+       status = ACCESS_ONCE(ads->status8);
+       if ((status & AR_TxDone) == 0)
                return -EINPROGRESS;
 
        ah->ts_tail = (ah->ts_tail + 1) % ah->ts_size;
@@ -253,57 +255,58 @@ static int ar9003_hw_proc_txdesc(struct ath_hw *ah, void *ds,
                return -EIO;
        }
 
+       if (status & AR_TxOpExceeded)
+               ts->ts_status |= ATH9K_TXERR_XTXOP;
+       ts->ts_rateindex = MS(status, AR_FinalTxIdx);
+       ts->ts_seqnum = MS(status, AR_SeqNum);
+       ts->tid = MS(status, AR_TxTid);
+
        ts->qid = MS(ads->ds_info, AR_TxQcuNum);
        ts->desc_id = MS(ads->status1, AR_TxDescId);
-       ts->ts_seqnum = MS(ads->status8, AR_SeqNum);
        ts->ts_tstamp = ads->status4;
        ts->ts_status = 0;
        ts->ts_flags  = 0;
 
-       if (ads->status3 & AR_ExcessiveRetries)
+       status = ACCESS_ONCE(ads->status2);
+       ts->ts_rssi_ctl0 = MS(status, AR_TxRSSIAnt00);
+       ts->ts_rssi_ctl1 = MS(status, AR_TxRSSIAnt01);
+       ts->ts_rssi_ctl2 = MS(status, AR_TxRSSIAnt02);
+       if (status & AR_TxBaStatus) {
+               ts->ts_flags |= ATH9K_TX_BA;
+               ts->ba_low = ads->status5;
+               ts->ba_high = ads->status6;
+       }
+
+       status = ACCESS_ONCE(ads->status3);
+       if (status & AR_ExcessiveRetries)
                ts->ts_status |= ATH9K_TXERR_XRETRY;
-       if (ads->status3 & AR_Filtered)
+       if (status & AR_Filtered)
                ts->ts_status |= ATH9K_TXERR_FILT;
-       if (ads->status3 & AR_FIFOUnderrun) {
+       if (status & AR_FIFOUnderrun) {
                ts->ts_status |= ATH9K_TXERR_FIFO;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->status8 & AR_TxOpExceeded)
-               ts->ts_status |= ATH9K_TXERR_XTXOP;
-       if (ads->status3 & AR_TxTimerExpired)
+       if (status & AR_TxTimerExpired)
                ts->ts_status |= ATH9K_TXERR_TIMER_EXPIRED;
-
-       if (ads->status3 & AR_DescCfgErr)
+       if (status & AR_DescCfgErr)
                ts->ts_flags |= ATH9K_TX_DESC_CFG_ERR;
-       if (ads->status3 & AR_TxDataUnderrun) {
+       if (status & AR_TxDataUnderrun) {
                ts->ts_flags |= ATH9K_TX_DATA_UNDERRUN;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->status3 & AR_TxDelimUnderrun) {
+       if (status & AR_TxDelimUnderrun) {
                ts->ts_flags |= ATH9K_TX_DELIM_UNDERRUN;
                ath9k_hw_updatetxtriglevel(ah, true);
        }
-       if (ads->status2 & AR_TxBaStatus) {
-               ts->ts_flags |= ATH9K_TX_BA;
-               ts->ba_low = ads->status5;
-               ts->ba_high = ads->status6;
-       }
-
-       ts->ts_rateindex = MS(ads->status8, AR_FinalTxIdx);
-
-       ts->ts_rssi = MS(ads->status7, AR_TxRSSICombined);
-       ts->ts_rssi_ctl0 = MS(ads->status2, AR_TxRSSIAnt00);
-       ts->ts_rssi_ctl1 = MS(ads->status2, AR_TxRSSIAnt01);
-       ts->ts_rssi_ctl2 = MS(ads->status2, AR_TxRSSIAnt02);
-       ts->ts_rssi_ext0 = MS(ads->status7, AR_TxRSSIAnt10);
-       ts->ts_rssi_ext1 = MS(ads->status7, AR_TxRSSIAnt11);
-       ts->ts_rssi_ext2 = MS(ads->status7, AR_TxRSSIAnt12);
-       ts->ts_shortretry = MS(ads->status3, AR_RTSFailCnt);
-       ts->ts_longretry = MS(ads->status3, AR_DataFailCnt);
-       ts->ts_virtcol = MS(ads->status3, AR_VirtRetryCnt);
-       ts->ts_antenna = 0;
-
-       ts->tid = MS(ads->status8, AR_TxTid);
+       ts->ts_shortretry = MS(status, AR_RTSFailCnt);
+       ts->ts_longretry = MS(status, AR_DataFailCnt);
+       ts->ts_virtcol = MS(status, AR_VirtRetryCnt);
+
+       status = ACCESS_ONCE(ads->status7);
+       ts->ts_rssi = MS(status, AR_TxRSSICombined);
+       ts->ts_rssi_ext0 = MS(status, AR_TxRSSIAnt10);
+       ts->ts_rssi_ext1 = MS(status, AR_TxRSSIAnt11);
+       ts->ts_rssi_ext2 = MS(status, AR_TxRSSIAnt12);
 
        memset(ads, 0, sizeof(*ads));
 

diff --git a/drivers/net/wireless/ath/ath9k/mac.h b/drivers/net/wireless/ath/ath9k/mac.h
index 538c676e799c07f0d807273d6d839ec33aa98baa..fdc25074ca1ff45459e6db18e16e6d12fabb04a5 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/mac.h
+++ b/drivers/net/wireless/ath/ath9k/mac.h
@@ -104,13 +104,11 @@ struct ath_tx_status {
        u32 ts_tstamp;
        u16 ts_seqnum;
        u8 ts_status;
-       u8 ts_ratecode;
        u8 ts_rateindex;
        int8_t ts_rssi;
        u8 ts_shortretry;
        u8 ts_longretry;
        u8 ts_virtcol;
-       u8 ts_antenna;
        u8 ts_flags;
        int8_t ts_rssi_ctl0;
        int8_t ts_rssi_ctl1;
@@ -121,7 +119,6 @@ struct ath_tx_status {
        u8 qid;
        u16 desc_id;
        u8 tid;
-       u8 pad[2];
        u32 ba_low;
        u32 ba_high;
        u32 evm0;