mac80211: avoid using ext NSS high BW if not supported
If the AP advertises inconsistent data, namely it has CCFS1 or CCFS2,
but doesn't advertise support for 160/80+80 bandwidth or "Extended NSS
BW Support", then we cannot use any MCSes in the the higher bandwidth.
Thus, avoid connecting with higher bandwidth since it's less efficient
that way.
Link: https://lore.kernel.org/r/20200528213443.0e55d40c3ccc.I6fd0b4708ebd087e5e46466c3e91f6efbcbef668@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 87dd003..e610482 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -3120,7 +3120,7 @@ bool ieee80211_chandef_ht_oper(const struct ieee80211_ht_operation *ht_oper,
return true;
}
-bool ieee80211_chandef_vht_oper(struct ieee80211_hw *hw,
+bool ieee80211_chandef_vht_oper(struct ieee80211_hw *hw, u32 vht_cap_info,
const struct ieee80211_vht_operation *oper,
const struct ieee80211_ht_operation *htop,
struct cfg80211_chan_def *chandef)
@@ -3132,6 +3132,10 @@ bool ieee80211_chandef_vht_oper(struct ieee80211_hw *hw,
u32 vht_cap;
bool support_80_80 = false;
bool support_160 = false;
+ u8 ext_nss_bw_supp = u32_get_bits(vht_cap_info,
+ IEEE80211_VHT_CAP_EXT_NSS_BW_MASK);
+ u8 supp_chwidth = u32_get_bits(vht_cap_info,
+ IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK);
if (!oper || !htop)
return false;
@@ -3151,11 +3155,48 @@ bool ieee80211_chandef_vht_oper(struct ieee80211_hw *hw,
IEEE80211_HT_OP_MODE_CCFS2_MASK)
>> IEEE80211_HT_OP_MODE_CCFS2_SHIFT;
- /* when parsing (and we know how to) CCFS1 and CCFS2 are equivalent */
ccf0 = ccfs0;
- ccf1 = ccfs1;
- if (!ccfs1 && ieee80211_hw_check(hw, SUPPORTS_VHT_EXT_NSS_BW))
+
+ /* if not supported, parse as though we didn't understand it */
+ if (!ieee80211_hw_check(hw, SUPPORTS_VHT_EXT_NSS_BW))
+ ext_nss_bw_supp = 0;
+
+ /*
+ * Cf. IEEE 802.11 Table 9-250
+ *
+ * We really just consider that because it's inefficient to connect
+ * at a higher bandwidth than we'll actually be able to use.
+ */
+ switch ((supp_chwidth << 4) | ext_nss_bw_supp) {
+ default:
+ case 0x00:
+ ccf1 = 0;
+ support_160 = false;
+ support_80_80 = false;
+ break;
+ case 0x01:
+ support_80_80 = false;
+ /* fall through */
+ case 0x02:
+ case 0x03:
ccf1 = ccfs2;
+ break;
+ case 0x10:
+ ccf1 = ccfs1;
+ break;
+ case 0x11:
+ case 0x12:
+ if (!ccfs1)
+ ccf1 = ccfs2;
+ else
+ ccf1 = ccfs1;
+ break;
+ case 0x13:
+ case 0x20:
+ case 0x23:
+ ccf1 = ccfs1;
+ break;
+ }
cf0 = ieee80211_channel_to_frequency(ccf0, chandef->chan->band);
cf1 = ieee80211_channel_to_frequency(ccf1, chandef->chan->band);
