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path: root/drivers/net/wireless/ath9k/hw.c
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Diffstat (limited to 'drivers/net/wireless/ath9k/hw.c')
-rw-r--r--drivers/net/wireless/ath9k/hw.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/drivers/net/wireless/ath9k/hw.c b/drivers/net/wireless/ath9k/hw.c
index 34474edefc97..c38a00bbce64 100644
--- a/drivers/net/wireless/ath9k/hw.c
+++ b/drivers/net/wireless/ath9k/hw.c
@@ -437,6 +437,25 @@ static void ath9k_hw_set_defaults(struct ath_hal *ah)
}
ah->ah_config.intr_mitigation = 1;
+
+ /*
+ * We need this for PCI devices only (Cardbus, PCI, miniPCI)
+ * _and_ if on non-uniprocessor systems (Multiprocessor/HT).
+ * This means we use it for all AR5416 devices, and the few
+ * minor PCI AR9280 devices out there.
+ *
+ * Serialization is required because these devices do not handle
+ * well the case of two concurrent reads/writes due to the latency
+ * involved. During one read/write another read/write can be issued
+ * on another CPU while the previous read/write may still be working
+ * on our hardware, if we hit this case the hardware poops in a loop.
+ * We prevent this by serializing reads and writes.
+ *
+ * This issue is not present on PCI-Express devices or pre-AR5416
+ * devices (legacy, 802.11abg).
+ */
+ if (num_possible_cpus() > 1)
+ ah->ah_config.serialize_regmode = SER_REG_MODE_AUTO;
}
static struct ath_hal_5416 *ath9k_hw_newstate(u16 devid,
@@ -668,7 +687,8 @@ static struct ath_hal *ath9k_hw_do_attach(u16 devid, struct ath_softc *sc,
}
if (ah->ah_config.serialize_regmode == SER_REG_MODE_AUTO) {
- if (ah->ah_macVersion == AR_SREV_VERSION_5416_PCI) {
+ if (ah->ah_macVersion == AR_SREV_VERSION_5416_PCI ||
+ (AR_SREV_9280(ah) && !ah->ah_isPciExpress)) {
ah->ah_config.serialize_regmode =
SER_REG_MODE_ON;
} else {