Re: [PATCH v3] mac80211: deprecate RX status noise

[Benoit PAPILLAULT <benoit.papillault@free.fr>]

Johannes Berg a écrit :
> The noise value as is won't be used, isn't
> filled by most drivers and doesn't really
> make a whole lot of sense on a per packet
> basis -- proper cfg80211 survey support in
> mac80211 will need to be different.
>
> Mark the struct member as deprecated so it
> will be removed from drivers.
>
> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
> ---
> I shouldn't be trying this at 9:30pm...
>
>
> Currently creates the following warnings:
>
> drivers/net/wireless/mwl8k.c:756: warning: ‘noise’ is deprecated
> drivers/net/wireless/mwl8k.c:858: warning: ‘noise’ is deprecated
> drivers/net/wireless/ath/ar9170/main.c:928: warning: ‘noise’ is deprecated
> drivers/net/wireless/ath/ath9k/common.c:215: warning: ‘noise’ is deprecated
> drivers/net/wireless/ath/ath5k/base.c:1941: warning: ‘noise’ is deprecated
> drivers/net/wireless/ath/ath5k/base.c:1942: warning: ‘noise’ is deprecated
> drivers/net/wireless/b43/xmit.c:613: warning: ‘noise’ is deprecated
> drivers/net/wireless/b43legacy/xmit.c:551: warning: ‘noise’ is deprecated
> drivers/net/wireless/libertas_tf/main.c:497: warning: ‘noise’ is deprecated
> drivers/net/wireless/rt2x00/rt2x00dev.c:437: warning: ‘noise’ is deprecated
> drivers/net/wireless/p54/txrx.c:353: warning: ‘noise’ is deprecated
> drivers/net/wireless/wl12xx/wl1251_rx.c:80: warning: ‘noise’ is deprecated
> drivers/net/wireless/wl12xx/wl1271_rx.c:139: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-3945.c:682: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-3945.c:685: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-3945.c:689: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-3945.c:697: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-3945.c:711: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-rx.c:1191: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-rx.c:1193: warning: ‘noise’ is deprecated
> drivers/net/wireless/iwlwifi/iwl-rx.c:1206: warning: ‘noise’ is deprecated
>
> I'll make patches for drivers when it becomes
> clear that it won't clash with any work others
> have pending.
>
>  include/net/mac80211.h     |    4 ++--
>  net/mac80211/debugfs_sta.c |    2 --
>  net/mac80211/rx.c          |    9 ---------
>  net/mac80211/sta_info.h    |    2 --
>  4 files changed, 2 insertions(+), 15 deletions(-)
>
> --- wireless-testing.orig/include/net/mac80211.h	2010-02-17 20:57:33.000000000 +0100
> +++ wireless-testing/include/net/mac80211.h	2010-02-17 21:25:46.000000000 +0100
> @@ -543,7 +543,7 @@ enum mac80211_rx_flags {
>   * @signal: signal strength when receiving this frame, either in dBm, in dB or
>   *	unspecified depending on the hardware capabilities flags
>   *	@IEEE80211_HW_SIGNAL_*
> - * @noise: noise when receiving this frame, in dBm.
> + * @noise: noise when receiving this frame, in dBm (DEPRECATED).
>   * @antenna: antenna used
>   * @rate_idx: index of data rate into band's supported rates or MCS index if
>   *	HT rates are use (RX_FLAG_HT)
> @@ -554,7 +554,7 @@ struct ieee80211_rx_status {
>  	enum ieee80211_band band;
>  	int freq;
>  	int signal;
> -	int noise;
> +	int noise __deprecated;
>  	int antenna;
>  	int rate_idx;
>  	int flag;
> --- wireless-testing.orig/net/mac80211/debugfs_sta.c	2010-02-17 21:20:49.000000000 +0100
> +++ wireless-testing/net/mac80211/debugfs_sta.c	2010-02-17 21:20:53.000000000 +0100
> @@ -57,7 +57,6 @@ STA_FILE(tx_filtered, tx_filtered_count,
>  STA_FILE(tx_retry_failed, tx_retry_failed, LU);
>  STA_FILE(tx_retry_count, tx_retry_count, LU);
>  STA_FILE(last_signal, last_signal, D);
> -STA_FILE(last_noise, last_noise, D);
>  STA_FILE(wep_weak_iv_count, wep_weak_iv_count, LU);
>  
>  static ssize_t sta_flags_read(struct file *file, char __user *userbuf,
> @@ -289,7 +288,6 @@ void ieee80211_sta_debugfs_add(struct st
>  	DEBUGFS_ADD(tx_retry_failed);
>  	DEBUGFS_ADD(tx_retry_count);
>  	DEBUGFS_ADD(last_signal);
> -	DEBUGFS_ADD(last_noise);
>  	DEBUGFS_ADD(wep_weak_iv_count);
>  	DEBUGFS_ADD(ht_capa);
>  }
> --- wireless-testing.orig/net/mac80211/rx.c	2010-02-17 21:20:32.000000000 +0100
> +++ wireless-testing/net/mac80211/rx.c	2010-02-17 21:26:31.000000000 +0100
> @@ -179,14 +179,6 @@ ieee80211_add_rx_radiotap_header(struct
>  		pos++;
>  	}
>  
> -	/* IEEE80211_RADIOTAP_DBM_ANTNOISE */
> -	if (local->hw.flags & IEEE80211_HW_NOISE_DBM) {
> -		*pos = status->noise;
> -		rthdr->it_present |=
> -			cpu_to_le32(1 << IEEE80211_RADIOTAP_DBM_ANTNOISE);
> -		pos++;
> -	}
> -
>  	/* IEEE80211_RADIOTAP_LOCK_QUALITY is missing */
>  
>  	/* IEEE80211_RADIOTAP_ANTENNA */
> @@ -1078,7 +1070,6 @@ ieee80211_rx_h_sta_process(struct ieee80
>  	sta->rx_fragments++;
>  	sta->rx_bytes += rx->skb->len;
>  	sta->last_signal = status->signal;
> -	sta->last_noise = status->noise;
>  
>  	/*
>  	 * Change STA power saving mode only at the end of a frame
> --- wireless-testing.orig/net/mac80211/sta_info.h	2010-02-17 21:20:39.000000000 +0100
> +++ wireless-testing/net/mac80211/sta_info.h	2010-02-17 21:20:44.000000000 +0100
> @@ -200,7 +200,6 @@ struct sta_ampdu_mlme {
>   * @rx_fragments: number of received MPDUs
>   * @rx_dropped: number of dropped MPDUs from this STA
>   * @last_signal: signal of last received frame from this STA
> - * @last_noise: noise of last received frame from this STA
>   * @last_seq_ctrl: last received seq/frag number from this STA (per RX queue)
>   * @tx_filtered_count: number of frames the hardware filtered for this STA
>   * @tx_retry_failed: number of frames that failed retry
> @@ -271,7 +270,6 @@ struct sta_info {
>  	unsigned long rx_fragments;
>  	unsigned long rx_dropped;
>  	int last_signal;
> -	int last_noise;
>  	__le16 last_seq_ctrl[NUM_RX_DATA_QUEUES];
>  
>  	/* Updated from TX status path only, no locking requirements */
>
>   
I just wrote an application that read "last_signal" and "last_noise" in 
order to compute the SNR value of all neighboring nodes in 
/sys/kernel/debug/ieee80211/phy0/stations. So, it is used and needed.

Being per packet or global, I'm not an RF engineer to say what's best, 
but even if it is global, "last_noise" would still be useful as "global 
noise when the last packets was received from this node".

My 2 cents,
Benoit