[PATCH ath-current] wifi: ath12k: don't advertise EHT-MCS15 to firmware unless we support it

[Baochen Qiang]

ath12k_peer_assoc_h_eht() copies the peer's EHT PHY capabilities into
the WMI peer assoc command as is, including the EHT-MCS15 support bits.
Firmware rate control enables EHT-MCS15 for TX whenever those bits are
set, without checking whether the local PHY supports MCS15.

Currently WCN7850 firmware does not support EHT-MCS15 for TX and does
not advertise it in its own EHT PHY capabilities. When connected to an
AP that advertises MCS15 support, rate control may still select
EHT-MCS15, and every PPDU at that rate is aborted by the PHY before it
goes on the air. TX then stops for minutes while the association stays
up, and frames sit in the queue until the firmware releases them as aged.

Keep only the peer's MCS15 support bits that we also support ourselves
to fix it. Chips that support MCS15 are not affected.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3

Fixes: 17bbb8aa74fd ("wifi: ath12k: prepare EHT peer assoc parameters")
Reported-by: Vladimir Petrzhikovskii <vladimir at dfb.sh>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=222136
Tested-by: Vladimir Petrzhikovskii <vladimir at dfb.sh>
Signed-off-by: Baochen Qiang <baochen.qiang at oss.qualcomm.com>
---
 drivers/net/wireless/ath/ath12k/mac.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
index 01f8c6572f65..8f37ec6af6d3 100644
--- a/drivers/net/wireless/ath/ath12k/mac.c
+++ b/drivers/net/wireless/ath/ath12k/mac.c
@@ -3366,6 +3366,7 @@ static void ath12k_peer_assoc_h_eht(struct ath12k *ar,
 	u32 *rx_mcs, *tx_mcs;
 	u16 *eht_mcs_mask;
 	u8 max_nss = 0;
+	u8 mcs15;
 
 	lockdep_assert_wiphy(ath12k_ar_to_hw(ar)->wiphy);
 
@@ -3416,6 +3417,16 @@ static void ath12k_peer_assoc_h_eht(struct ath12k *ar,
 	memcpy(arg->peer_eht_cap_phy, eht_cap->eht_cap_elem.phy_cap_info,
 	       sizeof(eht_cap->eht_cap_elem.phy_cap_info));
 
+	/*
+	 * Firmware rate control enables EHT-MCS15 based only on the peer's
+	 * MCS15 support bits, so keep only the ones we support ourselves.
+	 */
+	mcs15 = u8_get_bits(eht_cap->eht_cap_elem.phy_cap_info[6] &
+			    own_eht_cap->eht_cap_elem.phy_cap_info[6],
+			    IEEE80211_EHT_PHY_CAP6_MCS15_SUPP_MASK);
+	u8p_replace_bits(&((u8 *)arg->peer_eht_cap_phy)[6], mcs15,
+			 IEEE80211_EHT_PHY_CAP6_MCS15_SUPP_MASK);
+
 	rx_mcs = arg->peer_eht_rx_mcs_set;
 	tx_mcs = arg->peer_eht_tx_mcs_set;
 

---
base-commit: fab2e70afb13485ea4b198b204af33dd15b8132c
change-id: 20261023-ath12k-mcs15-818b3a574813

Best regards,
-- 
Baochen Qiang <baochen.qiang at oss.qualcomm.com>