[PATCH v3 2/2] wifi: ath9k: clear the PHY error filter when a spectral scan is disabled

["Nerijus Bendžiūnas" <nerijus.bendziunas@gmail.com>]

Triggering a spectral scan sets the PHY error bits in AR_RX_FILTER and
AR_PHY_ERR and sets AR_RXCFG_ZLFDMA. Disabling it clears none of them,
and ath9k_htc carries the hardware bits into every later filter update.
An idle AR9271 in monitor mode then keeps forwarding every PHY error
as a zero-length frame.

Clear all three on SPECTRAL_DISABLED unless radar detection is enabled,
which needs the same bits. AR_RXCFG_ZLFDMA must go too: with it set the
frames keep coming after the PHY error mask is cleared. As with the
enable path, firmware older than 1.4 still reads from the host.

Fixes: e93d083f42a1 ("ath9k: add spectral scan feature")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Nerijus Bendžiūnas <nerijus.bendziunas@gmail.com>
---
 .../net/wireless/ath/ath9k/common-spectral.c  |  6 +++++
 drivers/net/wireless/ath/ath9k/hw.c           | 23 +++++++++++++++++++
 drivers/net/wireless/ath/ath9k/hw.h           |  1 +
 3 files changed, 30 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/common-spectral.c b/drivers/net/wireless/ath/ath9k/common-spectral.c
index 73c1eb4ebe0e..841075d904f8 100644
--- a/drivers/net/wireless/ath/ath9k/common-spectral.c
+++ b/drivers/net/wireless/ath/ath9k/common-spectral.c
@@ -776,6 +776,12 @@ int ath9k_cmn_spectral_scan_config(struct ath_common *common,
 
 	ath_ps_ops(common)->wakeup(common);
 	ath9k_hw_ops(ah)->spectral_scan_config(ah, &spec_priv->spec_config);
+
+	/* Radar detection needs the same bits. */
+	if (spectral_mode == SPECTRAL_DISABLED &&
+	    !common->hw->conf.radar_enabled)
+		ath9k_hw_disable_rxfilter(ah, ATH9K_RX_FILTER_PHYRADAR |
+					      ATH9K_RX_FILTER_PHYERR);
 	ath_ps_ops(common)->restore(common);
 
 	spec_priv->spectral_mode = spectral_mode;
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index d62b6ff00d41..6f86a8967548 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -2928,6 +2928,29 @@ void ath9k_hw_enable_rxfilter(struct ath_hw *ah, u32 bits)
 }
 EXPORT_SYMBOL(ath9k_hw_enable_rxfilter);
 
+/*
+ * Counterpart of ath9k_hw_enable_rxfilter(). AR_RXCFG_ZLFDMA goes with the
+ * PHY error mask or the frames keep coming; callers clear all the PHY error
+ * bits together, as checking for a remaining one would need a read.
+ */
+void ath9k_hw_disable_rxfilter(struct ath_hw *ah, u32 bits)
+{
+	u32 phybits = 0;
+
+	if (bits & ATH9K_RX_FILTER_PHYRADAR)
+		phybits |= AR_PHY_ERR_RADAR;
+	if (bits & ATH9K_RX_FILTER_PHYERR)
+		phybits |= AR_PHY_ERR_OFDM_TIMING | AR_PHY_ERR_CCK_TIMING;
+
+	REG_CLR_BIT(ah, AR_RX_FILTER, bits);
+
+	if (phybits) {
+		REG_CLR_BIT(ah, AR_PHY_ERR, phybits);
+		REG_CLR_BIT(ah, AR_RXCFG, AR_RXCFG_ZLFDMA);
+	}
+}
+EXPORT_SYMBOL(ath9k_hw_disable_rxfilter);
+
 bool ath9k_hw_phy_disable(struct ath_hw *ah)
 {
 	if (ath9k_hw_mci_is_enabled(ah))
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index f102f73a0114..983146208f26 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -1056,6 +1056,7 @@ void ath9k_hw_get_channel_centers(struct ath_hw *ah,
 u32 ath9k_hw_getrxfilter(struct ath_hw *ah);
 void ath9k_hw_setrxfilter(struct ath_hw *ah, u32 bits);
 void ath9k_hw_enable_rxfilter(struct ath_hw *ah, u32 bits);
+void ath9k_hw_disable_rxfilter(struct ath_hw *ah, u32 bits);
 bool ath9k_hw_phy_disable(struct ath_hw *ah);
 bool ath9k_hw_disable(struct ath_hw *ah);
 void ath9k_hw_set_txpowerlimit(struct ath_hw *ah, u32 limit, bool test);
-- 
2.55.0