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Date:   Wed, 30 Dec 2020 18:57:49 +0800
From:   Wen Gong <wgong@codeaurora.org>
To:     Shay Bar <shay.bar@celeno.com>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org, aviad.brikman@celeno.com,
        eliav.farber@celeno.com, linux-wireless-owner@vger.kernel.org,
        ath11k@lists.infradead.org
Subject: Re: [PATCH] wireless: fix wrong 160/80+80 MHz setting
In-Reply-To: <20200826143139.25976-1-shay.bar@celeno.com>
References: <20200826143139.25976-1-shay.bar@celeno.com>
Message-ID: <34893f267fa37b43d21c19d4c08c090e@codeaurora.org>
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On 2020-08-26 22:31, Shay Bar wrote:
> Fix cfg80211_chandef_usable():
> consider IEEE80211_VHT_CAP_EXT_NSS_BW when verifying 160/80+80 MHz.
> 
When station with below 2 bit and connect to a 160MHZ 11ac mode AP, it 
will try to use 160Mhz width after this patch,
but it does not support 160M in fact according spec of IEEE 802.11
.... .... .... .... .... .... .... 00.. = Supported Channel Width Set: 
Neither 160MHz nor 80+80 supported (0x0)
01.. .... .... .... .... .... .... .... = Extended NSS BW Support: 0x1

refer to spec of IEEE 802.11.
Table 9-250—Setting of the Supported Channel Width Set subfield and 
Extended NSS BW Support subfield at a STA transmitting the VHT 
Capabilities Information field
value of the 160Mhz is 1/2 in the table for upper configure.
NOTE 2—1/2× or 3/4× Max VHT NSS support might end up being 0, indicating 
no support.

> Based on:
> "Table 9-272 — Setting of the Supported Channel Width Set subfield and
> Extended NSS BW
> Support subfield at a STA transmitting the VHT Capabilities Information 
> field"
> From "Draft P802.11REVmd_D3.0.pdf"
> 
> Signed-off-by: Aviad Brikman <aviad.brikman@celeno.com>
> Signed-off-by: Shay Bar <shay.bar@celeno.com>
> ---
>  net/wireless/chan.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/net/wireless/chan.c b/net/wireless/chan.c
> index 90f0f82cd9ca..a51d11d3be33 100644
> --- a/net/wireless/chan.c
> +++ b/net/wireless/chan.c
> @@ -912,6 +912,7 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
>         struct ieee80211_sta_vht_cap *vht_cap;
>         struct ieee80211_edmg *edmg_cap;
>         u32 width, control_freq, cap;
> +       bool support_80_80 = false;
> 
>         if (WARN_ON(!cfg80211_chandef_valid(chandef)))
>                 return false;
> @@ -979,9 +980,16 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
>                         return false;
>                 break;
>         case NL80211_CHAN_WIDTH_80P80:
> -               cap = vht_cap->cap & 
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
> +               cap = vht_cap->cap;
> +               support_80_80 =
> +                       ((cap &
> +                         
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ) ||
> +                       (cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ 
> &&
> +                        cap & IEEE80211_VHT_CAP_EXT_NSS_BW_MASK) ||
> +                       ((cap & IEEE80211_VHT_CAP_EXT_NSS_BW_MASK) >>
> +                                   IEEE80211_VHT_CAP_EXT_NSS_BW_SHIFT 
> > 1));
>                 if (chandef->chan->band != NL80211_BAND_6GHZ &&
> -                   cap != 
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
> +                   !support_80_80)
>                         return false;
>                 /* fall through */
>         case NL80211_CHAN_WIDTH_80:
> @@ -1001,7 +1009,8 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
>                         return false;
>                 cap = vht_cap->cap & 
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
>                 if (cap != IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ &&
> -                   cap != 
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
> +                   cap != 
> IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ &&
> +                   !(vht_cap->cap & 
> IEEE80211_VHT_CAP_EXT_NSS_BW_MASK))
>                         return false;
>                 break;
>         default:
> --
> 2.17.1
> 
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