wifi: ath9k: Clear DMA descriptors without memset

Clear ath9k DMA descriptors with explicit status word stores instead of
memset(). The descriptor rings are coherent DMA memory, which may be
mapped uncached on 32-bit powerpc. The optimized memset() path can use
dcbz there and trigger an alignment warning.

Use WRITE_ONCE() for the descriptor status words so the compiler keeps
the clears as ordinary stores instead of folding them back into bulk
memset(). This covers AR9003 TX status descriptors as well as the RX
status area cleared when setting up RX descriptors.

Assisted-by: Codex:GPT-5.5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260517042716.2218386-1-rosenp@gmail.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>

diff --git a/drivers/net/wireless/ath/ath9k/ar9002_mac.c b/drivers/net/wireless/ath/ath9k/ar9002_mac.c
index b70cd4af1ae0aa32c6f4974a6115d7acf6ff3944..e355f94a93904e340c120f78552614c8db51d56c 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ar9002_mac.c
+++ b/drivers/net/wireless/ath/ath9k/ar9002_mac.c
@@ -403,6 +403,19 @@ static int ar9002_hw_get_duration(struct ath_hw *ah, const void *ds, int index)
        }
 }
 
+static void ath9k_hw_clear_rxdesc_status(struct ar5416_desc *ads)
+{
+       WRITE_ONCE(ads->u.rx.status0, 0);
+       WRITE_ONCE(ads->u.rx.status1, 0);
+       WRITE_ONCE(ads->u.rx.status2, 0);
+       WRITE_ONCE(ads->u.rx.status3, 0);
+       WRITE_ONCE(ads->u.rx.status4, 0);
+       WRITE_ONCE(ads->u.rx.status5, 0);
+       WRITE_ONCE(ads->u.rx.status6, 0);
+       WRITE_ONCE(ads->u.rx.status7, 0);
+       WRITE_ONCE(ads->u.rx.status8, 0);
+}
+
 void ath9k_hw_setuprxdesc(struct ath_hw *ah, struct ath_desc *ds,
                          u32 size, u32 flags)
 {
@@ -412,7 +425,7 @@ void ath9k_hw_setuprxdesc(struct ath_hw *ah, struct ath_desc *ds,
        if (flags & ATH9K_RXDESC_INTREQ)
                ads->ds_ctl1 |= AR_RxIntrReq;
 
-       memset(&ads->u.rx, 0, sizeof(ads->u.rx));
+       ath9k_hw_clear_rxdesc_status(ads);
 }
 EXPORT_SYMBOL(ath9k_hw_setuprxdesc);
 

diff --git a/drivers/net/wireless/ath/ath9k/ar9003_mac.c b/drivers/net/wireless/ath/ath9k/ar9003_mac.c
index a8bc003077dc446f3f907b49ea75dcc68d3d9438..97027d286317edca3795c9b4c7cf0329e5e066d1 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ar9003_mac.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_mac.c
@@ -352,6 +352,19 @@ static bool ar9003_hw_get_isr(struct ath_hw *ah, enum ath9k_int *masked,
        return true;
 }
 
+static void ath9k_hw_clear_txstatus(struct ar9003_txs *ads)
+{
+       WRITE_ONCE(ads->ds_info, 0);
+       WRITE_ONCE(ads->status1, 0);
+       WRITE_ONCE(ads->status2, 0);
+       WRITE_ONCE(ads->status3, 0);
+       WRITE_ONCE(ads->status4, 0);
+       WRITE_ONCE(ads->status5, 0);
+       WRITE_ONCE(ads->status6, 0);
+       WRITE_ONCE(ads->status7, 0);
+       WRITE_ONCE(ads->status8, 0);
+}
+
 static int ar9003_hw_proc_txdesc(struct ath_hw *ah, void *ds,
                                 struct ath_tx_status *ts)
 {
@@ -370,7 +383,7 @@ static int ar9003_hw_proc_txdesc(struct ath_hw *ah, void *ds,
            (MS(ads->ds_info, AR_TxRxDesc) != 1)) {
                ath_dbg(ath9k_hw_common(ah), XMIT,
                        "Tx Descriptor error %x\n", ads->ds_info);
-               memset(ads, 0, sizeof(*ads));
+               ath9k_hw_clear_txstatus(ads);
                return -EIO;
        }
 
@@ -427,7 +440,7 @@ static int ar9003_hw_proc_txdesc(struct ath_hw *ah, void *ds,
        ts->ts_rssi_ext1 = MS(status, AR_TxRSSIAnt11);
        ts->ts_rssi_ext2 = MS(status, AR_TxRSSIAnt12);
 
-       memset(ads, 0, sizeof(*ads));
+       ath9k_hw_clear_txstatus(ads);
 
        return 0;
 }
@@ -591,10 +604,12 @@ EXPORT_SYMBOL(ath9k_hw_process_rxdesc_edma);
 
 void ath9k_hw_reset_txstatus_ring(struct ath_hw *ah)
 {
+       int i;
+
        ah->ts_tail = 0;
 
-       memset((void *) ah->ts_ring, 0,
-               ah->ts_size * sizeof(struct ar9003_txs));
+       for (i = 0; i < ah->ts_size; i++)
+               ath9k_hw_clear_txstatus(&ah->ts_ring[i]);
 
        ath_dbg(ath9k_hw_common(ah), XMIT,
                "TS Start 0x%x End 0x%x Virt %p, Size %d\n",