| Message ID | 19cbe5dd1d7f0e194ed40c8db2cf2beffa3ae167.camel@freebox.fr (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | [RFC] mac80211: fix VHT 160Mhz bandwidth when using extended NSS on PHY with NSS ratio | expand |
On 5/16/2022 1:39 AM, Maxime Bizon wrote: > > A PHY supporting 160Mhz with a reduced number of NSS may not have any note correct abbreviation is: MHz and it is suggested to use a space to separate the value from the units > of the IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK bits set. > > For exemple, the QCA9984 is 4x4, but can only do 2x2 VHT160 or s/exemple/example/ > 80+80. The corresponding VHT capabilities should be: > - IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK == 0 > - Extended NSS BW == 2 > > If we use that hardware in AP mode, and a 160Mhz 2x2 STA without NSS > restriction connects to it, then that STA will set > IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK to 1. > > The usual logic of using bitwise-and with our own capabilities does > not work here, the current code clears the SUPP_CHAN_WIDTH bits and > resolve STA bandwidth to 80Mhz instead of 160Mhz, fix this. > > Signed-off-by: Maxime Bizon <mbizon@freebox.fr> > --- > net/mac80211/vht.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c > index e856f9092137..7ef93adc4f24 100644 > --- a/net/mac80211/vht.c > +++ b/net/mac80211/vht.c > @@ -230,9 +230,11 @@ ieee80211_vht_cap_ie_to_sta_vht_cap(struct ieee80211_sub_if_data *sdata, > sizeof(struct ieee80211_vht_mcs_info)); > > /* copy EXT_NSS_BW Support value or remove the capability */ > - if (ieee80211_hw_check(&sdata->local->hw, SUPPORTS_VHT_EXT_NSS_BW)) > + if (ieee80211_hw_check(&sdata->local->hw, SUPPORTS_VHT_EXT_NSS_BW)) { > + vht_cap->cap |= cap_info & > + IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK; > vht_cap->cap |= (cap_info & IEEE80211_VHT_CAP_EXT_NSS_BW_MASK); > - else > + } else per the coding style when you use braces on any leg of if/else, use them on all legs > vht_cap->vht_mcs.tx_highest &= > ~cpu_to_le16(IEEE80211_VHT_EXT_NSS_BW_CAPABLE); >
Applied on 5.19 and worked. AP: QCA9984 STA：AX201 Before patch: iw dev wlan-ax201 link rx bitrate: 866 MBit/s VHT-MCS 9 160MHz short GI VHT-NSS 1 tx bitrate: 866 MBit/s VHT-MCS 9 80MHz short GI VHT-NSS 2 After patch: rx bitrate: 866 MBit/s VHT-MCS 9 160MHz short GI VHT-NSS 1 tx bitrate: 866 MBit/s VHT-MCS 9 160MHz short GI VHT-NSS 1 Notice that the tx rate did not change and the NSS reduced from 2 to 1. But actually it should support VHT-NSS 2 and achieve 1733 MBit/s at least for rx bitrate (verified this with the same AP/STA using another OS, and iperf showed 1.2GBit/s). Do you have any idea to fix that? Although it is beyond the scope of this patch. with iw 5.19 ax201 showed VHT RX highest supported: 0 Mbps VHT TX highest supported: 0 Mbps VHT extended NSS: supported
diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c index e856f9092137..7ef93adc4f24 100644 --- a/net/mac80211/vht.c +++ b/net/mac80211/vht.c @@ -230,9 +230,11 @@ ieee80211_vht_cap_ie_to_sta_vht_cap(struct ieee80211_sub_if_data *sdata, sizeof(struct ieee80211_vht_mcs_info)); /* copy EXT_NSS_BW Support value or remove the capability */ - if (ieee80211_hw_check(&sdata->local->hw, SUPPORTS_VHT_EXT_NSS_BW)) + if (ieee80211_hw_check(&sdata->local->hw, SUPPORTS_VHT_EXT_NSS_BW)) { + vht_cap->cap |= cap_info & + IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK; vht_cap->cap |= (cap_info & IEEE80211_VHT_CAP_EXT_NSS_BW_MASK); - else + } else vht_cap->vht_mcs.tx_highest &= ~cpu_to_le16(IEEE80211_VHT_EXT_NSS_BW_CAPABLE);
A PHY supporting 160Mhz with a reduced number of NSS may not have any of the IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK bits set. For exemple, the QCA9984 is 4x4, but can only do 2x2 VHT160 or 80+80. The corresponding VHT capabilities should be: - IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK == 0 - Extended NSS BW == 2 If we use that hardware in AP mode, and a 160Mhz 2x2 STA without NSS restriction connects to it, then that STA will set IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK to 1. The usual logic of using bitwise-and with our own capabilities does not work here, the current code clears the SUPP_CHAN_WIDTH bits and resolve STA bandwidth to 80Mhz instead of 160Mhz, fix this. Signed-off-by: Maxime Bizon <mbizon@freebox.fr> --- net/mac80211/vht.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)