Mediatek's chipsets MT7927 and MT7925 with Windows driver 5.4.0.3044
(and earlier versions) set the IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_IN_2G
bit in 5 & 6Ghz band, which is supposed to be reserved. Currently, the
kernel assumes a reserved bit to be set to 0 and uses the bit value to
deduce that the current band used is 2.4GHz.
This causes the kernel to miscalculate mcs_nss_size to 3 bytes,
resulting in incorrect rx/tx nss map, so the sta is believed to have
0 NSS for 160/320.
Signed-off-by: Pablo Martin-Gomez <pmartin-gomez@xxxxxxxxxx>
---
include/linux/ieee80211.h | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 16741e542e81..2e813824d52a 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -3196,14 +3196,17 @@ ieee80211_eht_mcs_nss_size(const struct ieee80211_he_cap_elem *he_cap,
{
u8 count = 0;
- /* on 2.4 GHz, if it supports 40 MHz, the result is 3 */
- if (he_cap->phy_cap_info[0] &
- IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_IN_2G)
- return 3;
+ /* 20 MHz-only non-AP STA */
+ if (!from_ap && (he_cap->phy_cap_info[0] &
+ (IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_IN_2G |
+ IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_80MHZ_IN_5G |
+ IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_160MHZ_IN_5G |
+ IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_80PLUS80_MHZ_IN_5G)) == 0)
+ return 4;
- /* on 2.4 GHz, these three bits are reserved, so should be 0 */
if (he_cap->phy_cap_info[0] &
- IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_80MHZ_IN_5G)
+ (IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_IN_2G |
+ IEEE80211_HE_PHY_CAP0_CHANNEL_WIDTH_SET_40MHZ_80MHZ_IN_5G))
count += 3;
if (he_cap->phy_cap_info[0] &
--
2.43.0
