[PATCH v2,2/2] wifi: mac80211: Refactor STA CSA parsing flow

[Johannes Berg]

On Mon, 2023-11-13 at 10:11 +0800, Michael-CY Lee wrote:
> The Wi-Fi Standard (IEEE 802.11-2020 9.4.2.160) initially specified that
> the Wide Bandwidth Channel Switch (WBCS) IE subfields have same definitions
> as the S1G or VHT Operation Information according to the operating band.
> 
> However, it did not change the definitions in the amendment for 6 GHz
> (IEEE 802.11ax-2021), so the logic remain the same for handling the WBCS
> IE even if there is no VHT mode in 6 GHz.
> 
> Now the Wi-Fi Standard draft (IEEE P80211be D3.2 9.4.2.159) modifies the
> defitions, making the WBCS IE subfields follow the definitions of S1G,

type - definitions

> VHT and HE Operation Information in S1G, 5 GHz and 6 GHz band, respectively.
> 
> APs in 6 GHz band might use the VHT or HE Operation Information to build
> a WBCS IE according to the Wi-Fi Standard they follow. Originally, the STA

Probably should say "Element" in place of all those "IE" - the spec
stopped calling them "Information Elements" a long time ago :)

> just parsed the WBCS IE as VHT Operation Inforamtion, which was wrong if
> the AP was actually build the IE by the HE Operation Information.
> 
> To avoid the ambiguity, STA should prefer the op_class in the Extended
> Channel Switch Announcement (ECSA) IE rathen than the WBCS IE. If the ECSA

typo - rather

> IE is not presented in a channel switch to 6 GHz, the STA should be aware
> of the possible ambiguity when parsing the WBCS IE.
> 
> To derive the correct bandwidtin in use, the STA should check the

typo - bandwidth in

> +	case 4:
> +		/* 320 MHz bandwidth
> +		 * TODO channel switch to 320 MHz bandwidth should be indiated
> +		 * by Bandwidth Indication IE (IEEE P80211be D3.2 9.4.2.159)
> +		 */
> +		he_6ghz_oper->control = IEEE80211_EHT_OPER_CHAN_WIDTH_320MHZ;
> +		break;

I'm not sure what this TODO was meant to refer to, but I do know that
D4.1 made some changes here, maybe we should check those? I haven't even
checked what the changes are though.

In any case, checking with a newer draft and using that would seem
useful?

Haven't really read all the other things here yet, this just caught my
eye since I also just heard about D4.1 changes, but I don't have that or
even the old stuff all in my head right now.

johannes