ath9k_hw: improve performance for AR934x v1.3+

AR934x v1.3 no longer needs the DCU backoff reduction workaround for
preventing rx overruns, but in turn needs the number of usable Tx
buffers to be reduced slightly.

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

1 files changed, 10 insertions, 5 deletions

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 01e97ce438ba..15dfefcf2d0f 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1172,6 +1172,7 @@ u32 ath9k_regd_get_ctl(struct ath_regulatory *reg, struct ath9k_channel *chan)
 static inline void ath9k_hw_set_dma(struct ath_hw *ah)
 {
         struct ath_common *common = ath9k_hw_common(ah);
+        int txbuf_size;
 
         ENABLE_REGWRITE_BUFFER(ah);
 
@@ -1225,13 +1226,17 @@ static inline void ath9k_hw_set_dma(struct ath_hw *ah)
                  * So set the usable tx buf size also to half to
                  * avoid data/delimiter underruns
                  */
-                REG_WRITE(ah, AR_PCU_TXBUF_CTRL,
-                          AR_9285_PCU_TXBUF_CTRL_USABLE_SIZE);
-        } else if (!AR_SREV_9271(ah)) {
-                REG_WRITE(ah, AR_PCU_TXBUF_CTRL,
-                          AR_PCU_TXBUF_CTRL_USABLE_SIZE);
+                txbuf_size = AR_9285_PCU_TXBUF_CTRL_USABLE_SIZE;
+        } else if (AR_SREV_9340_13_OR_LATER(ah)) {
+                /* Uses fewer entries for AR934x v1.3+ to prevent rx overruns */
+                txbuf_size = AR_9340_PCU_TXBUF_CTRL_USABLE_SIZE;
+        } else {
+                txbuf_size = AR_PCU_TXBUF_CTRL_USABLE_SIZE;
         }
 
+        if (!AR_SREV_9271(ah))
+                REG_WRITE(ah, AR_PCU_TXBUF_CTRL, txbuf_size);
+
         REGWRITE_BUFFER_FLUSH(ah);
 
         if (AR_SREV_9300_20_OR_LATER(ah))