ath9k_hw: disabled PAPRD for AR9003

AR9003's PAPRD was enabled prematurely, and is causing some
large discrepancies on throughput and network connectivity.
For example downlink (RX) throughput against an AR9280 AP
can vary widlely from 43-73 Mbit/s while disabling this
gets AR9382 (2x2) up to around 93 Mbit/s in a 2.4 GHz HT20 setup.

Cc: stable@kernel.org
Cc: Paul Shaw <paul.shaw@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

Author: Luis R. Rodriguez

drivers/net/wireless/ath/ath9k/hw.c

@@ -369,6 +369,9 @@ static void ath9k_hw_init_config(struct ath_hw *ah)
 	else
 		ah->config.ht_enable = 0;
 
+	/* PAPRD needs some more work to be enabled */
+	ah->config.paprd_disable = 1;
+
 	ah->config.rx_intr_mitigation = true;
 	ah->config.pcieSerDesWrite = true;
 
@@ -1933,7 +1936,8 @@ int ath9k_hw_fill_cap_info(struct ath_hw *ah)
 		pCap->rx_status_len = sizeof(struct ar9003_rxs);
 		pCap->tx_desc_len = sizeof(struct ar9003_txc);
 		pCap->txs_len = sizeof(struct ar9003_txs);
-		if (ah->eep_ops->get_eeprom(ah, EEP_PAPRD))
+		if (!ah->config.paprd_disable &&
+		    ah->eep_ops->get_eeprom(ah, EEP_PAPRD))
 			pCap->hw_caps |= ATH9K_HW_CAP_PAPRD;
 	} else {
 		pCap->tx_desc_len = sizeof(struct ath_desc);

drivers/net/wireless/ath/ath9k/hw.h

@@ -225,6 +225,7 @@ struct ath9k_ops_config {
 	u32 pcie_waen;
 	u8 analog_shiftreg;
 	u8 ht_enable;
+	u8 paprd_disable;
 	u32 ofdm_trig_low;
 	u32 ofdm_trig_high;
 	u32 cck_trig_high;