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-rw-r--r--sys/conf/NOTES9
-rw-r--r--sys/conf/options1
-rw-r--r--sys/dev/ath/ath_hal/ar5212/ar5212_reset.c8
3 files changed, 18 insertions, 0 deletions
diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index f0cc9a0..cc1964d 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -2091,6 +2091,15 @@ device ath_hal # pci/cardbus chip support
#device ath_rf5413
#device ath_ar5416 # AR5416 chips
options AH_SUPPORT_AR5416 # enable AR5416 tx/rx descriptors
+# All of the AR5212 parts have a problem when paired with the AR71xx
+# CPUS. These parts have a bug that triggers a fatal bus error on the AR71xx
+# only. Details of the exact nature of the bug are sketchy, but some can be
+# found at https://forum.openwrt.org/viewtopic.php?pid=70060 on pages 4, 5 and
+# 6. This option enables this workaround. There is a performance penalty
+# for this work around, but without it things don't work at all. The DMA
+# from the card usually bursts 128 bytes, but on the affected CPUs, only
+# 4 are safe.
+options AH_RXCFG_SDMAMW_4BYTES
#device ath_ar9160 # AR9160 chips
#device ath_ar9280 # AR9280 chips
#device ath_ar9285 # AR9285 chips
diff --git a/sys/conf/options b/sys/conf/options
index fabc0bf..8f1dcaa 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -771,6 +771,7 @@ AH_PRIVATE_DIAG opt_ah.h
AH_NEED_DESC_SWAP opt_ah.h
AH_USE_INIPDGAIN opt_ah.h
AH_MAXCHAN opt_ah.h
+AH_RXCFG_SDMAMW_4BYTES opt_ah.h
# options for the Broadcom BCM43xx driver (bwi)
BWI_DEBUG opt_bwi.h
diff --git a/sys/dev/ath/ath_hal/ar5212/ar5212_reset.c b/sys/dev/ath/ath_hal/ar5212/ar5212_reset.c
index fc937ea..8e6341a 100644
--- a/sys/dev/ath/ath_hal/ar5212/ar5212_reset.c
+++ b/sys/dev/ath/ath_hal/ar5212/ar5212_reset.c
@@ -283,6 +283,14 @@ ar5212Reset(struct ath_hal *ah, HAL_OPMODE opmode,
regWrites = ath_hal_ini_write(ah, &ahp->ah_ini_modes, modesIndex, 0);
regWrites = write_common(ah, &ahp->ah_ini_common, bChannelChange,
regWrites);
+#ifdef AH_RXCFG_SDMAMW_4BYTES
+ /*
+ * Nala doesn't work with 128 byte bursts on pb42(hydra) (ar71xx),
+ * use 4 instead. Enabling it on all platforms would hurt performance,
+ * so we only enable it on the ones that are affected by it.
+ */
+ OS_REG_WRITE(ah, AR_RXCFG, 0);
+#endif
ahp->ah_rfHal->writeRegs(ah, modesIndex, freqIndex, regWrites);
OS_MARK(ah, AH_MARK_RESET_LINE, __LINE__);
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