[PATCH v2] wifi: mac80211: skip ieee80211_verify_sta_ht_mcs_support check in non-strict mode

[Rio Liu]

Some Xfinity XB8 firmware advertises >1 spatial stream MCS indexes in
their basic HT-MCS set. On cards with lower spatial streams, the check
would fail, and we'd be stuck with no HT when in fact work fine with its
own supported rate. This change makes it so the check is only performed
in strict mode.

Fixes: 574faa0e936d ("wifi: mac80211: add HT and VHT basic set verification")
Signed-off-by: Rio Liu <rio@xxxxxx>
---
v2 changes:
- update comment to include Xfinity router model
- generalize comment to include devices with only single spatial stream
- add Fixes tag
- add wifi: mac80211: to patch title

Link to v1: https://lore.kernel.org/linux-wireless/AKVRf_yEu2mRCJekCJpre5xXMuHa_3_dO7_H1UU8fiKZRjJUf96ZKepiR999NwpiVwmzWBYoKipBpx1rqZatVihMYOCvANUnbeoyI2U7ct0=@r26.me/T/#u

 net/mac80211/mlme.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 810bea1aacc5..44cb826263ba 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -419,6 +419,15 @@ ieee80211_verify_sta_ht_mcs_support(struct ieee80211_sub_if_data *sdata,
 	memcpy(&sta_ht_cap, &sband->ht_cap, sizeof(sta_ht_cap));
 	ieee80211_apply_htcap_overrides(sdata, &sta_ht_cap);

+	/*
+	 * Some Xfinity XB8 firmware advertises >1 spatial stream MCS indexes in
+	 * their basic HT-MCS set. On cards with lower spatial streams, the check
+	 * would fail, and we'd be stuck with no HT when it in fact work fine with
+	 * its own supported rate. So check it only in strict mode.
+	 */
+	if (!ieee80211_hw_check(&sdata->local->hw, STRICT))
+		return true;
+
 	/*
 	 * P802.11REVme/D7.0 - 6.5.4.2.4
 	 * ...

base-commit: d65b175cfac64ee65506eea7fa573d291a9694ca
--
2.53.0