Re: [RFC/RFT] iwlagn: use cts-to-self protection on 5000 adapters series

[Dan Williams <dcbw@redhat.com>]

On Thu, 2011-05-12 at 17:25 +0200, Stanislaw Gruszka wrote:
> This patch fixes 802.11n performance regression I 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 results test 5x downloading of approximately 700MB iso image
> on wreless-testing kernel:
> 
> 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 unpached 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 unpached
> 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
> 
> I think patch also helps with
> 
> 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
> 
> on 2.6.35 kernel, that I can see happens randomly on that version, but
> I'm not 100% sure about that.
> 
> This is partial revert of:
> 
> commit 94597ab23ea10b3bdcba534be00a9f7b35791c07
> Author: Johannes Berg <johannes.berg@intel.com>
> Date:   Mon Aug 9 10:57:02 2010 -0700
> 
>     iwlagn: fix rts cts protection
> 
> so I'm not sure if patch does not broke things, which that
> commit fixes.
> ---
>  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 98f81df..06949c1 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-5000.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-5000.c
> @@ -433,7 +433,6 @@ 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 b12c72d..23fa93d 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
> @@ -163,17 +163,9 @@ 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 0238743..96a5832 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
> @@ -326,6 +326,14 @@ int iwlagn_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
>  			return 0;
>  	}
>  
> +	/*
> +	 * force CTS-to-self frames protection if RTS-CTS is not preffered

Spelling nit: "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;