CC'ing linux-wireless
Am Mittwoch, 2. März 2011 schrieb Johannes Berg:
> On Wed, 2011-03-02 at 09:53 +0100, Helmut Schaa wrote:
> > Am Mittwoch, 2. März 2011 schrieb Johannes Berg:
> > > On Wed, 2011-03-02 at 09:37 +0100, Helmut Schaa wrote:
> > > > Currently hostapd will force HT Mixed Mode if at least one non-GF STA is
> > > > associated. This will force _all_ HT transmissions to be protected.
> > > >
> > > > 802.11n-2009 doesn't require HT Mixed Mode to be used in case of non-GF
> > > > STAs but instead the HT information element contains a flag if non-GF
> > > > STAs are present. All STAs are required to protect GF transmissions in
> > > > that case. Hence, setting HT Mixed mode if non-GF STAs are present is
> > > > superfluous.
> > >
> > > It seems like this would still be relevant for the AP's TX?
> >
> > Why? hostapd will configure the new ht_opmode (including the non-GF-STA flag)
> > to the driver. And the driver should do the right thing and enable protection only
> > for GF transmissions in that case, no?
Ok, doing a quick grep through drivers/net/wireless/*:
wl1271 doesn't honor this flag right now but seems trivial to fix:
1347 int wl1271_acx_set_ht_information(struct wl1271 *wl,
1348 u16 ht_operation_mode)
1349 {
...
1361 acx->ht_protection =
1362 (u8)(ht_operation_mode & IEEE80211_HT_OP_MODE_PROTECTION);
1363 acx->rifs_mode = 0;
1364 acx->gf_protection = 0;
1365 acx->ht_tx_burst_limit = 0;
1366 acx->dual_cts_protection = 0;
rt2800 does the right thing:
1240 static void rt2800_config_ht_opmode(struct rt2x00_dev *rt2x00dev,
1241 struct rt2x00lib_erp *erp)
1242 {
1243 bool any_sta_nongf = !!(erp->ht_opmode &
1244 IEEE80211_HT_OP_MODE_NON_GF_STA_PRSNT);
...
1310 /* check for STAs not supporting greenfield mode */
1311 if (any_sta_nongf)
1312 gf20_mode = gf40_mode = 2;
mwl8k also doesn't honor it, no idea how to fix it:
2603 static int
2604 mwl8k_cmd_set_aid(struct ieee80211_hw *hw,
2605 struct ieee80211_vif *vif, u32 legacy_rate_mask)
2606 {
...
2623 switch (vif->bss_conf.ht_operation_mode &
2624 IEEE80211_HT_OP_MODE_PROTECTION) {
2625 case IEEE80211_HT_OP_MODE_PROTECTION_20MHZ:
2626 prot_mode = MWL8K_FRAME_PROT_11N_HT_40MHZ_ONLY;
2627 break;
2628 case IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED:
2629 prot_mode = MWL8K_FRAME_PROT_11N_HT_ALL;
2630 break;
2631 default:
2632 prot_mode = MWL8K_FRAME_PROT_DISABLED;
2633 break;
2634 }
2635 }
2636 cmd->protection_mode = cpu_to_le16(prot_mode);
iwlwifi/iwllegacy seems correct (as long as the fw is doing the right thing):
560 void iwlagn_bss_info_changed(struct ieee80211_hw *hw,
561 struct ieee80211_vif *vif,
562 struct ieee80211_bss_conf *bss_conf,
563 u32 changes)
564 {
...
608 ctx->ht.protection = bss_conf->ht_operation_mode &
609 IEEE80211_HT_OP_MODE_PROTECTION;
610 ctx->ht.non_gf_sta_present = !!(bss_conf->ht_operation_mode &
611 IEEE80211_HT_OP_MODE_NON_GF_STA_PRSNT);
612 iwlagn_check_needed_chains(priv, ctx, bss_conf);
613 iwl_set_rxon_ht(priv, &priv->current_ht_config);
Helmut
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