openwrt/package/kernel/mac80211/patches/355-ath9k_hw-check-if-the-chip-failed-to-wake-up.patch
Felix Fietkau f9022964cf ath9k: add stability fixes for long standing hang issues (FS#13, #34, #373, #383)
The radio would stop communicating completely. This issue was easiest to
trigger on AR913x devices, e.g. the TP-Link TL-WR1043ND, but other
hardware was occasionally affected as well.

The most critical issue was a race condition in disabling/enabling IRQs
between the IRQ handler and the IRQ processing tasklet

Signed-off-by: Felix Fietkau <nbd@nbd.name>
2017-01-25 17:28:17 +01:00

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From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 25 Jan 2017 12:58:17 +0100
Subject: [PATCH] ath9k_hw: check if the chip failed to wake up
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>
---
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1624,6 +1624,10 @@ 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);