Hi,
On 26/08/2025 19:26, Miri Korenblit wrote:
From: Benjamin Berg <benjamin.berg@xxxxxxxxx>
The EHT PHY requirements state that 80 MHz must be supported on the 5
and 6 GHz bands unless the STA is 20 MHz only. So if the channel width
is limited to 40 MHz on a band other than 2.4 GHz, then disable EHT and
downgrade to HE.
This is wrong one way or another.
If we follow the 802.11 standard strictly [I'm going to use annex B's
items so it is easier to follow], we are implementing EHTP3.3, so a non
20 MHz-Only STA has to support 80 MHz channel width, therefore a 40 MHz
(max) STA would not be compliant and we have to downgrade it. The issue
is that HEP3.3 also requires that a non 20 MHz-Only HE STA has to
support 80 MHz channel width, therefore downgrading to HE is not ok. We
have the same issue with VHTP3.3 that requires a VHT STA to support 80
MHz channel width, therefore downgrading to VHT is not okay either. So
that means that the strictly compliant approach would be to disallow a
40 MHz STA in the 6 GHz band and downgrade a 40 MHz STA to HT in the
5GHz band.
If we follow the 802.11 standard more liberally, we never enforced
VHTP3.3 nor HEP3.3, so why begin now with EHTP3.3?
The primary case where this can happen is if the hardware disables
puncturing using IEEE80211_HW_DISALLOW_PUNCTURING.
Signed-off-by: Benjamin Berg <benjamin.berg@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@xxxxxxxxx>
Best regards,
Pablo MG
