[PATCH 4.4 07/50] ath9k_hw: check if the chip failed to wake up

From: Greg Kroah-Hartman
Date: Fri Apr 27 2018 - 10:01:03 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Felix Fietkau <nbd@xxxxxxxx>

commit a34d0a0da1abae46a5f6ebd06fb0ec484ca099d9 upstream.

In an RFC patch, Sven Eckelmann and Simon Wunderlich reported:

"QCA 802.11n chips (especially AR9330/AR9340) sometimes end up in a
state in which a read of AR_CFG always returns 0xdeadbeef.
This should not happen when when the power_mode of the device is

Include the check for the default register state in the existing MAC
hang check.

Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxxxx>
Cc: Amit Pundir <amit.pundir@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/net/wireless/ath/ath9k/hw.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1595,6 +1595,10 @@ bool ath9k_hw_check_alive(struct ath_hw
int count = 50;
u32 reg, last_val;

+ /* Check if chip failed to wake up */
+ if (REG_READ(ah, AR_CFG) == 0xdeadbeef)
+ return false;
if (AR_SREV_9300(ah))
return !ath9k_hw_detect_mac_hang(ah);