From: Sathishkumar Muruganandam <quic_murugana@quicinc.com>

Currently, ieee80211_ie_build_he_oper() lacks support for 320 MHz handling
(already noted as a TODO). This is because 320 MHz is not included in
IEEE 802.11-ax. However, IEEE 802.11-be introduces 320 MHz support and if
the chandef indicates a 320 MHz bandwidth and is used directly as it is, it
will result in an incorrect HE Operation Information Element.

In order to support EHT 320 MHz, HE Operation Element should indicate
bandwidth as 160 MHz only. In EHT Operation IE, the correct bandwidth will
be present. Devices capable of EHT can parse EHT Information Element and
connect in 320 MHz and other HE capable devices can parse HE and can
connect in 160 MHz.

Add support to downgrade the bandwidth in ieee80211_ie_build_he_oper()
during 320 MHz operation and advertise it.

Signed-off-by: Sathishkumar Muruganandam <quic_murugana@quicinc.com>
Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
---
 net/mac80211/util.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index a4e1301cc999d24d6ab1bd899742a2ff04229040..c88ce537aaa7ea5d59dc42e5f30805c6eb4a5c6d 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2762,6 +2762,7 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
 {
 	struct ieee80211_he_operation *he_oper;
 	struct ieee80211_he_6ghz_oper *he_6ghz_op;
+	struct cfg80211_chan_def he_chandef;
 	u32 he_oper_params;
 	u8 ie_len = 1 + sizeof(struct ieee80211_he_operation);
 
@@ -2793,27 +2794,33 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
 	if (chandef->chan->band != NL80211_BAND_6GHZ)
 		goto out;
 
+	cfg80211_chandef_create(&he_chandef, chandef->chan, NL80211_CHAN_NO_HT);
+	he_chandef.center_freq1 = chandef->center_freq1;
+	he_chandef.center_freq2 = chandef->center_freq2;
+	he_chandef.width = chandef->width;
+
 	/* TODO add VHT operational */
 	he_6ghz_op = (struct ieee80211_he_6ghz_oper *)pos;
 	he_6ghz_op->minrate = 6; /* 6 Mbps */
 	he_6ghz_op->primary =
-		ieee80211_frequency_to_channel(chandef->chan->center_freq);
+		ieee80211_frequency_to_channel(he_chandef.chan->center_freq);
 	he_6ghz_op->ccfs0 =
-		ieee80211_frequency_to_channel(chandef->center_freq1);
-	if (chandef->center_freq2)
+		ieee80211_frequency_to_channel(he_chandef.center_freq1);
+	if (he_chandef.center_freq2)
 		he_6ghz_op->ccfs1 =
-			ieee80211_frequency_to_channel(chandef->center_freq2);
+			ieee80211_frequency_to_channel(he_chandef.center_freq2);
 	else
 		he_6ghz_op->ccfs1 = 0;
 
-	switch (chandef->width) {
+	switch (he_chandef.width) {
 	case NL80211_CHAN_WIDTH_320:
-		/*
-		 * TODO: mesh operation is not defined over 6GHz 320 MHz
-		 * channels.
+		/* Downgrade EHT 320 MHz BW to 160 MHz for HE and set new
+		 * center_freq1
 		 */
-		WARN_ON(1);
-		break;
+		ieee80211_chandef_downgrade(&he_chandef, NULL);
+		he_6ghz_op->ccfs0 =
+			ieee80211_frequency_to_channel(he_chandef.center_freq1);
+		fallthrough;
 	case NL80211_CHAN_WIDTH_160:
 		/* Convert 160 MHz channel width to new style as interop
 		 * workaround.
@@ -2821,7 +2828,7 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
 		he_6ghz_op->control =
 			IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_160MHZ;
 		he_6ghz_op->ccfs1 = he_6ghz_op->ccfs0;
-		if (chandef->chan->center_freq < chandef->center_freq1)
+		if (he_chandef.chan->center_freq < he_chandef.center_freq1)
 			he_6ghz_op->ccfs0 -= 8;
 		else
 			he_6ghz_op->ccfs0 += 8;

-- 
2.34.1

On Tue Nov 19, 2024 at 5:27 AM CET, Aditya Kumar Singh wrote:
> From: Sathishkumar Muruganandam <quic_murugana@quicinc.com>
>
> Currently, ieee80211_ie_build_he_oper() lacks support for 320 MHz handling
> (already noted as a TODO). This is because 320 MHz is not included in
> IEEE 802.11-ax. However, IEEE 802.11-be introduces 320 MHz support and if
> the chandef indicates a 320 MHz bandwidth and is used directly as it is, it
> will result in an incorrect HE Operation Information Element.
>
> In order to support EHT 320 MHz, HE Operation Element should indicate
> bandwidth as 160 MHz only. In EHT Operation IE, the correct bandwidth will
> be present. Devices capable of EHT can parse EHT Information Element and
> connect in 320 MHz and other HE capable devices can parse HE and can
> connect in 160 MHz.
>
> Add support to downgrade the bandwidth in ieee80211_ie_build_he_oper()
> during 320 MHz operation and advertise it.
>
> Signed-off-by: Sathishkumar Muruganandam <quic_murugana@quicinc.com>
> Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
> ---
>  net/mac80211/util.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index a4e1301cc999d24d6ab1bd899742a2ff04229040..c88ce537aaa7ea5d59dc42e5f30805c6eb4a5c6d 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -2762,6 +2762,7 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
>  {
>  	struct ieee80211_he_operation *he_oper;
>  	struct ieee80211_he_6ghz_oper *he_6ghz_op;
> +	struct cfg80211_chan_def he_chandef;
>  	u32 he_oper_params;
>  	u8 ie_len = 1 + sizeof(struct ieee80211_he_operation);
>  
> @@ -2793,27 +2794,33 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
>  	if (chandef->chan->band != NL80211_BAND_6GHZ)
>  		goto out;
>  
> +	cfg80211_chandef_create(&he_chandef, chandef->chan, NL80211_CHAN_NO_HT);
> +	he_chandef.center_freq1 = chandef->center_freq1;
> +	he_chandef.center_freq2 = chandef->center_freq2;
> +	he_chandef.width = chandef->width;
> +
>  	/* TODO add VHT operational */
>  	he_6ghz_op = (struct ieee80211_he_6ghz_oper *)pos;
>  	he_6ghz_op->minrate = 6; /* 6 Mbps */
>  	he_6ghz_op->primary =
> -		ieee80211_frequency_to_channel(chandef->chan->center_freq);
> +		ieee80211_frequency_to_channel(he_chandef.chan->center_freq);
>  	he_6ghz_op->ccfs0 =
> -		ieee80211_frequency_to_channel(chandef->center_freq1);
> -	if (chandef->center_freq2)
> +		ieee80211_frequency_to_channel(he_chandef.center_freq1);
> +	if (he_chandef.center_freq2)
>  		he_6ghz_op->ccfs1 =
> -			ieee80211_frequency_to_channel(chandef->center_freq2);
> +			ieee80211_frequency_to_channel(he_chandef.center_freq2);
>  	else
>  		he_6ghz_op->ccfs1 = 0;
>  
> -	switch (chandef->width) {
> +	switch (he_chandef.width) {
>  	case NL80211_CHAN_WIDTH_320:
> -		/*
> -		 * TODO: mesh operation is not defined over 6GHz 320 MHz
> -		 * channels.
> +		/* Downgrade EHT 320 MHz BW to 160 MHz for HE and set new
> +		 * center_freq1
>  		 */
> -		WARN_ON(1);
> -		break;
> +		ieee80211_chandef_downgrade(&he_chandef, NULL);
> +		he_6ghz_op->ccfs0 =
> +			ieee80211_frequency_to_channel(he_chandef.center_freq1);
I don't understand the full implication of those two calls but I made 320MHz
work by doing the same as for 160 but with +/- = 16 instead of 8.
> +		fallthrough;
>  	case NL80211_CHAN_WIDTH_160:
>  		/* Convert 160 MHz channel width to new style as interop
>  		 * workaround.
> @@ -2821,7 +2828,7 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
>  		he_6ghz_op->control =
>  			IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_160MHZ;
>  		he_6ghz_op->ccfs1 = he_6ghz_op->ccfs0;
> -		if (chandef->chan->center_freq < chandef->center_freq1)
> +		if (he_chandef.chan->center_freq < he_chandef.center_freq1)
>  			he_6ghz_op->ccfs0 -= 8;
>  		else
>  			he_6ghz_op->ccfs0 += 8;

Something along this lines seemed to be enough:

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index a4e1301cc999..f24479f74813 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2808,18 +2808,15 @@ u8 *ieee80211_ie_build_he_oper(u8 *pos, const struct cfg80211_chan_def *chandef)
 
 	switch (chandef->width) {
 	case NL80211_CHAN_WIDTH_320:
-		/*
-		 * TODO: mesh operation is not defined over 6GHz 320 MHz
-		 * channels.
-		 */
-		WARN_ON(1);
-		break;
+		if (chandef->chan->center_freq < chandef->center_freq1)
+			he_6ghz_op->ccfs0 -= 16;
+		else
+			he_6ghz_op->ccfs0 += 16;
+		fallthrough;
 	case NL80211_CHAN_WIDTH_160:
 		/* Convert 160 MHz channel width to new style as interop
 		 * workaround.
 		 */
-		he_6ghz_op->control =
-			IEEE80211_HE_6GHZ_OPER_CTRL_CHANWIDTH_160MHZ;
 		he_6ghz_op->ccfs1 = he_6ghz_op->ccfs0;
 		if (chandef->chan->center_freq < chandef->center_freq1)
 			he_6ghz_op->ccfs0 -= 8;
-- 
2.47.0