[PATCH F-15 0/1] iwlwifi: fix general 11n instability (common bug 648732)

[Stanislaw Gruszka]

This patch is missed fix for fedora common bug 648732 on F-15.
Other patches needed to address the bug are already in 2.6.38.
This patch was posted to stable, bud did not get applied on
2.6.38 (it's in 2.6.39.2+)

[PATCH 2.6.38] iwlagn: use cts-to-self protection on 5000 adapters series

[Stanislaw Gruszka]

This patch fixes 802.11n stability and performance regression we have
since 2.6.35. It boost performance on my 5GHz N-only network from about
5MB/s to 8MB/s. Similar percentage boost can be observed on 2.4 GHz.

These are test results of 5x downloading of approximately 700MB iso
image:

vanilla: 5.27 5.22 4.94 4.47 5.31 ; avr 5.0420 std 0.35110
patched: 8.07 7.95 8.06 7.99 7.96 ; avr 8.0060 std 0.055946

This was achieved with NetworkManager configured to do not perform
periodical scans, by configuring constant BSSID. With periodical scans,
after some time, performance downgrade to unpatched driver level, like
in example below:

patched: 7.40 7.61 4.28 4.37 4.80 avr 5.6920 std 1.6683

However patch still make better here, since similar test on unpatched
driver make link disconnects with below messages after some time:

wlan1: authenticate with 00:23:69:35:d1:3f (try 1)
wlan1: authenticate with 00:23:69:35:d1:3f (try 2)
wlan1: authenticate with 00:23:69:35:d1:3f (try 3)
wlan1: authentication with 00:23:69:35:d1:3f timed out

On 2.6.35 kernel patch helps against connection hangs with messages:

iwlagn 0000:20:00.0: queue 10 stuck 3 time. Fw reload.
iwlagn 0000:20:00.0: On demand firmware reload
iwlagn 0000:20:00.0: Stopping AGG while state not ON or starting

Signed-off-by: Stanislaw Gruszka 
---
 drivers/net/wireless/iwlwifi/iwl-5000.c     |    1 -
 drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c |   12 ++----------
 drivers/net/wireless/iwlwifi/iwl-agn-rxon.c |    8 ++++++++
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-5000.c b/drivers/net/wireless/iwlwifi/iwl-5000.c
index 537fb8c..909cc30 100644
--- a/drivers/net/wireless/iwlwifi/iwl-5000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-5000.c
@@ -517,7 +517,6 @@ static struct iwl_base_params iwl5000_base_params = {
 };
 static struct iwl_ht_params iwl5000_ht_params = {
    .ht_greenfield_support = true,
-	.use_rts_for_aggregation = true, /* use rts/cts protection */
 };

#define IWL_DEVICE_5000						\
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c b/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
index 366340f..89762a7 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
@@ -217,17 +217,9 @@ static void iwlagn_tx_cmd_protection(struct iwl_priv *priv,
    			     __le16 fc, __le32 *tx_flags)
 {
    if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS ||
-	    info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT) {
+	    info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT ||
+	    info->flags & IEEE80211_TX_CTL_AMPDU)
    	*tx_flags |= TX_CMD_FLG_PROT_REQUIRE_MSK;
-		return;
-	}
-
-	if (priv->cfg->ht_params &&
-	    priv->cfg->ht_params->use_rts_for_aggregation &&
-	    info->flags & IEEE80211_TX_CTL_AMPDU) {
-		*tx_flags |= TX_CMD_FLG_PROT_REQUIRE_MSK;
-		return;
-	}
 }

/* Calc max signal level (dBm) among 3 possible receivers */
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
index ee802fe..b19fb85 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
@@ -145,6 +145,14 @@ int iwlagn_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
    /* always get timestamp with Rx frame */
    ctx->staging.flags |= RXON_FLG_TSF2HOST_MSK;

+	/*
+	 * force CTS-to-self frames protection if RTS-CTS is not preferred
+	 * one aggregation protection method
+	 */
+	if (!(priv->cfg->ht_params &&
+	      priv->cfg->ht_params->use_rts_for_aggregation))
+		ctx->staging.flags |= RXON_FLG_SELF_CTS_EN;
+
    if ((ctx->vif && ctx->vif->bss_conf.use_short_slot) ||
        !(ctx->staging.flags & RXON_FLG_BAND_24G_MSK))
    	ctx->staging.flags |= RXON_FLG_SHORT_SLOT_MSK;

[Kyle McMartin]

On Mon, Jun 20, 2011 at 04:11:21PM +0200, Stanislaw Gruszka wrote:
> This patch is missed fix for fedora common bug 648732 on F-15.
> Other patches needed to address the bug are already in 2.6.38.
> This patch was posted to stable, bud did not get applied on
> 2.6.38 (it's in 2.6.39.2+)

Thanks, applied. If you have users waiting on this fix, they can try the
build
http://koji.fedoraproject.org/koji/buildinfo?buildID=248960
until it gets pushed in an update.

regards, Kyle

[Danny Stieben]

I know this may only be a little relevant, but are there going to be any
more 2.6.39 builds? I'd just like to know because if not then I may
switch back to 2.6.38 so I can get ya'lls kernel fixes.

Thanks,