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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Felix Fietkau <nbd@nbd.name>,
        Kalle Valo <kvalo@qca.qualcomm.com>,
        Amit Pundir <amit.pundir@linaro.org>
Subject: [PATCH 4.9 16/74] ath9k_hw: check if the chip failed to wake up
Date:   Fri, 27 Apr 2018 15:58:06 +0200
Message-Id: <20180427135710.573193299@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <nbd@nbd.name>

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
ATH9K_PM_AWAKE."

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

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -1603,6 +1603,10 @@ 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);