Subject: [PATCH 4.9.0-rc5] AR9300 calibration problems with antenna selected

From: [email-masked] (Krzysztof Hałasa)
Date: Tue, 15 Nov 2016 10:56:37 +0100

Hi,

I recently tried to select a single antenna on AR9300 and it works for
30 seconds only. The subsequent calibration makes the RX signal level to
drop from the usual -30/-40 dBm to -70/-80 dBm, and the transmission
practically stops.

With the attached patch it works, though selecting the antenna doesn't
seem to have any visible effect, at least with "iw wlanX station dump"
(perhaps it works for TX).

I'm using ad-hoc mode:

rmmod ath9k
modprobe ath9k
iw dev wlan0 set type ibss
iw phy phyX set antenna 2
ip link set up dev wlan0
iw dev wlan0 set bitrates legacy-2.4 18
iw dev wlan0 ibss join nameXXX freqYYY
ip addr add ZZZ broadcast + dev wlan0

The card in question is Mikrotik (Routerboard) R11e-2HPnD mPCIe adapter:
AR9580 Wireless Network Adapter (rev 01), ID 168c:0033, subsystem
19b6:d016.
ieee80211 phy0: Atheros AR9300 Rev:4 mem=0xc0f40000, irq=334
https://routerboard.com/R11e-2HPnD

Linux 4.9.0-rc5.

Is there a better way?

Signed-off-by: Krzysztof Halasa <[email-masked]>

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index e9f32b5..7f17e5d 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -2245,7 +2245,7 @@ static int ath9k_set_antenna(struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant)
 		return 0;
 
 	/* AR9100 runs into calibration issues if not all rx chains are enabled */
-	if (AR_SREV_9100(ah))
+	if (AR_SREV_9100(ah) || AR_SREV_9300(ah))
 		ah->rxchainmask = 0x7;
 	else
 		ah->rxchainmask = fill_chainmask(ah->caps.rx_chainmask, rx_ant);

-- 
Krzysztof Halasa

Industrial Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland