[PATCH v2] mac80211: allow overriding station bandwidth.

[PATCH v2] mac80211: allow overriding station bandwidth.

[greearb]

From: Ben Greear <greearb@candelatech.com>

This allows one to disable VHT160 (or 80+80) on hardware
that might otherwise try to use it.

Signed-off-by: Ben Greear <greearb@candelatech.com>
---
v2: Change description

 include/linux/ieee80211.h |  1 +
 net/mac80211/main.c       |  1 +
 net/mac80211/vht.c        | 23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index a80516f..e5dc3a8 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1542,6 +1542,7 @@ struct ieee80211_vht_operation {
 #define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ		0x00000004
 #define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ	0x00000008
 #define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK			0x0000000C
+#define IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT			2
 #define IEEE80211_VHT_CAP_RXLDPC				0x00000010
 #define IEEE80211_VHT_CAP_SHORT_GI_80				0x00000020
 #define IEEE80211_VHT_CAP_SHORT_GI_160				0x00000040
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index ec5587d..1447b47 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -464,6 +464,7 @@ static const struct ieee80211_ht_cap mac80211_ht_capa_mod_mask = {
 static const struct ieee80211_vht_cap mac80211_vht_capa_mod_mask = {
 	.vht_cap_info =
 		cpu_to_le32(IEEE80211_VHT_CAP_RXLDPC |
+			    IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK |
 			    IEEE80211_VHT_CAP_SHORT_GI_80 |
 			    IEEE80211_VHT_CAP_SHORT_GI_160 |
 			    IEEE80211_VHT_CAP_RXSTBC_1 |
diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c
index 720c64c..5684e13 100644
--- a/net/mac80211/vht.c
+++ b/net/mac80211/vht.c
@@ -56,6 +56,29 @@ void ieee80211_apply_vhtcap_overrides(struct ieee80211_sub_if_data *sdata,
 	__check_vhtcap_disable(sdata, vht_cap,
 			       IEEE80211_VHT_CAP_TX_ANTENNA_PATTERN);
 
+	/* Allow disabling 160Mhz or 80+80 */
+	if (sdata->u.mgd.vht_capa_mask.vht_cap_info &
+	    cpu_to_le32(IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK)) {
+		u32 cap, n;
+
+		n = le32_to_cpu(sdata->u.mgd.vht_capa.vht_cap_info) &
+			IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
+		n >>= IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT;
+		cap = vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
+		cap >>= IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT;
+
+		if (n < cap) {
+			vht_cap->cap &=
+				~IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
+			vht_cap->cap |=
+				n << IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_SHIFT;
+
+			/* Cannot do short GI 160 if we cannot do 160 or 80+80 */
+			if (n == 0)
+				vht_cap->cap &= ~IEEE80211_VHT_CAP_SHORT_GI_160;
+		}
+	}
+
 	/* Allow user to decrease AMPDU length exponent */
 	if (sdata->u.mgd.vht_capa_mask.vht_cap_info &
 	    cpu_to_le32(IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK)) {
-- 
2.4.11

Re: [PATCH v2] mac80211: allow overriding station bandwidth.

[Johannes Berg]

On Wed, 2017-02-15 at 17:16 -0800, greearb@candelatech.com wrote:
> From: Ben Greear <greearb@candelatech.com>
> 
> This allows one to disable VHT160 (or 80+80) on hardware
> that might otherwise try to use it.

I just decided against applying this now because of the changing VHT
extended NSS BW stuff. This would in that case not actually override
the 160/80+80 capability, which would probably actually be the right
thing given how this works (mask & shift stuff), but without also
allowing to override the *new* things you'd not actually gain the
ability to get rid of 160/80+80... so overall I think right now that's
just confusing things even more.

johannes