* Re: [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs
[not found] ` <1299056258.4076.8.camel@jlt3.sipsolutions.net>
@ 2011-03-02 9:13 ` Helmut Schaa
2011-03-02 9:18 ` Johannes Berg
0 siblings, 1 reply; 4+ messages in thread
From: Helmut Schaa @ 2011-03-02 9:13 UTC (permalink / raw)
To: Johannes Berg; +Cc: hostap, Jouni Malinen, linux-wireless
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs
2011-03-02 9:13 ` [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs Helmut Schaa
@ 2011-03-02 9:18 ` Johannes Berg
2011-03-02 9:20 ` Helmut Schaa
0 siblings, 1 reply; 4+ messages in thread
From: Johannes Berg @ 2011-03-02 9:18 UTC (permalink / raw)
To: Helmut Schaa; +Cc: hostap, Jouni Malinen, linux-wireless
On Wed, 2011-03-02 at 10:13 +0100, Helmut Schaa wrote:
> 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);
Well, you forgot to quote this from iwl-agn-rs.c:
static bool rs_use_green(struct ieee80211_sta *sta)
{
struct iwl_station_priv *sta_priv = (void *)sta->drv_priv;
struct iwl_rxon_context *ctx = sta_priv->common.ctx;
return (sta->ht_cap.cap & IEEE80211_HT_CAP_GRN_FLD) &&
!(ctx->ht.non_gf_sta_present);
}
But it looks like it's doing the right thing.
johannes
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs
2011-03-02 9:18 ` Johannes Berg
@ 2011-03-02 9:20 ` Helmut Schaa
2011-03-02 9:24 ` Johannes Berg
0 siblings, 1 reply; 4+ messages in thread
From: Helmut Schaa @ 2011-03-02 9:20 UTC (permalink / raw)
To: Johannes Berg; +Cc: hostap, Jouni Malinen, linux-wireless
Am Mittwoch, 2. März 2011 schrieb Johannes Berg:
> On Wed, 2011-03-02 at 10:13 +0100, Helmut Schaa wrote:
>
> > 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);
>
> Well, you forgot to quote this from iwl-agn-rs.c:
>
> static bool rs_use_green(struct ieee80211_sta *sta)
> {
> struct iwl_station_priv *sta_priv = (void *)sta->drv_priv;
> struct iwl_rxon_context *ctx = sta_priv->common.ctx;
>
> return (sta->ht_cap.cap & IEEE80211_HT_CAP_GRN_FLD) &&
> !(ctx->ht.non_gf_sta_present);
> }
Hmm, that looks a bit fishy as well. iwlagn should be allowed to use GF
in that case, it just needs to protect it.
> But it looks like it's doing the right thing.
>From a protection POV, yes.
Helmut
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs
2011-03-02 9:20 ` Helmut Schaa
@ 2011-03-02 9:24 ` Johannes Berg
0 siblings, 0 replies; 4+ messages in thread
From: Johannes Berg @ 2011-03-02 9:24 UTC (permalink / raw)
To: Helmut Schaa; +Cc: hostap, Jouni Malinen, linux-wireless
On Wed, 2011-03-02 at 10:20 +0100, Helmut Schaa wrote:
> > static bool rs_use_green(struct ieee80211_sta *sta)
> > {
> > struct iwl_station_priv *sta_priv = (void *)sta->drv_priv;
> > struct iwl_rxon_context *ctx = sta_priv->common.ctx;
> >
> > return (sta->ht_cap.cap & IEEE80211_HT_CAP_GRN_FLD) &&
> > !(ctx->ht.non_gf_sta_present);
> > }
>
> Hmm, that looks a bit fishy as well. iwlagn should be allowed to use GF
> in that case, it just needs to protect it.
Right. That looks like it'd be a bit more tricky, and I don't think I
care right now.
johannes
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-03-02 9:13 ` [PATCH] hostapd: Don't force HT Mixed Mode for non-GF STAs Helmut Schaa
2011-03-02 9:18 ` Johannes Berg
2011-03-02 9:20 ` Helmut Schaa
2011-03-02 9:24 ` Johannes Berg
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