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Subject: Re: [PATCH 5.9 v2 2/3] mac80211: factor out code to look up the
 average packet length duration for a rate
To:     Felix Fietkau <nbd@nbd.name>, linux-wireless@vger.kernel.org
Cc:     johannes@sipsolutions.net
References: <20200821163045.62140-1-nbd@nbd.name>
 <20200821163045.62140-2-nbd@nbd.name>
From:   Sebastian Gottschall <s.gottschall@dd-wrt.com>
Message-ID: <add72d7d-40fc-dd42-64db-c016280453dd@dd-wrt.com>
Date:   Fri, 21 Aug 2020 22:43:27 +0200
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Am 21.08.2020 um 18:30 schrieb Felix Fietkau:
> This will be used to enhance AQL estimated aggregation length
>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
> v2: add missing return code check
>   net/mac80211/airtime.c | 121 +++++++++++++++++++++++++----------------
>   1 file changed, 74 insertions(+), 47 deletions(-)
>
> diff --git a/net/mac80211/airtime.c b/net/mac80211/airtime.c
> index 656c9a033714..ba95f4ee1f71 100644
> --- a/net/mac80211/airtime.c
> +++ b/net/mac80211/airtime.c
> @@ -405,18 +405,14 @@ ieee80211_calc_legacy_rate_duration(u16 bitrate, bool short_pre,
>   	return duration;
>   }
>   
> -u32 ieee80211_calc_rx_airtime(struct ieee80211_hw *hw,
> -			      struct ieee80211_rx_status *status,
> -			      int len)
> +static u32 ieee80211_get_rate_duration(struct ieee80211_hw *hw,
> +				       struct ieee80211_rx_status *status,
> +				       u32 *overhead)
>   {
> -	struct ieee80211_supported_band *sband;
> -	const struct ieee80211_rate *rate;
>   	bool sgi = status->enc_flags & RX_ENC_FLAG_SHORT_GI;
> -	bool sp = status->enc_flags & RX_ENC_FLAG_SHORTPRE;
>   	int bw, streams;
>   	int group, idx;
>   	u32 duration;
> -	bool cck;
>   
>   	switch (status->bw) {
>   	case RATE_INFO_BW_20:
> @@ -437,20 +433,6 @@ u32 ieee80211_calc_rx_airtime(struct ieee80211_hw *hw,
>   	}
>   
>   	switch (status->encoding) {
> -	case RX_ENC_LEGACY:
> -		if (WARN_ON_ONCE(status->band > NL80211_BAND_5GHZ))
> -			return 0;
> -
> -		sband = hw->wiphy->bands[status->band];
> -		if (!sband || status->rate_idx >= sband->n_bitrates)
> -			return 0;
> -
> -		rate = &sband->bitrates[status->rate_idx];
> -		cck = rate->flags & IEEE80211_RATE_MANDATORY_B;
> -
> -		return ieee80211_calc_legacy_rate_duration(rate->bitrate, sp,
> -							   cck, len);
> -
>   	case RX_ENC_VHT:
>   		streams = status->nss;
>   		idx = status->rate_idx;
> @@ -477,13 +459,47 @@ u32 ieee80211_calc_rx_airtime(struct ieee80211_hw *hw,
>   
>   	duration = airtime_mcs_groups[group].duration[idx];
>   	duration <<= airtime_mcs_groups[group].shift;
> +	*overhead = 36 + (streams << 2);
> +
> +	return duration;
> +}
> +
> +
> +u32 ieee80211_calc_rx_airtime(struct ieee80211_hw *hw,
> +			      struct ieee80211_rx_status *status,
> +			      int len)
> +{
> +	struct ieee80211_supported_band *sband;
> +	u32 duration, overhead = 0;
> +
> +	if (status->encoding == RX_ENC_LEGACY) {
> +		const struct ieee80211_rate *rate;
> +		bool sp = status->enc_flags & RX_ENC_FLAG_SHORTPRE;
> +		bool cck;
> +
> +		if (WARN_ON_ONCE(status->band > NL80211_BAND_5GHZ))
> +			return 0;
> +
> +		sband = hw->wiphy->bands[status->band];
> +		if (!sband || status->rate_idx >= sband->n_bitrates)
> +			return 0;
> +
> +		rate = &sband->bitrates[status->rate_idx];
> +		cck = rate->flags & IEEE80211_RATE_MANDATORY_B;
> +
> +		return ieee80211_calc_legacy_rate_duration(rate->bitrate, sp,
> +							   cck, len);
> +	}
> +
> +	duration = ieee80211_get_rate_duration(hw, status, &overhead);
> +	if (!duration)
> +		return 0;
> +
>   	duration *= len;
>   	duration /= AVG_PKT_SIZE;
>   	duration /= 1024;
>   
> -	duration += 36 + (streams << 2);
> -
> -	return duration;
> +	return duration + overhead;
>   }
>   EXPORT_SYMBOL_GPL(ieee80211_calc_rx_airtime);
>   
> @@ -530,46 +546,57 @@ static bool ieee80211_fill_rate_info(struct ieee80211_hw *hw,
>   	return false;
>   }
>   
> -static u32 ieee80211_calc_tx_airtime_rate(struct ieee80211_hw *hw,
> -					  struct ieee80211_tx_rate *rate,
> -					  struct rate_info *ri,
> -					  u8 band, int len)
> +static int ieee80211_fill_rx_status(struct ieee80211_rx_status *stat,
> +				    struct ieee80211_hw *hw,
> +				    struct ieee80211_tx_rate *rate,
> +				    struct rate_info *ri, u8 band, int len)
>   {
> -	struct ieee80211_rx_status stat = {
> -		.band = band,
> -	};
> +	memset(stat, 0, sizeof(*stat));
> +	stat->band = band;
>   
> -	if (ieee80211_fill_rate_info(hw, &stat, band, ri))
> -		goto out;
> +	if (ieee80211_fill_rate_info(hw, stat, band, ri))
> +		return 0;
>   
>   	if (rate->idx < 0 || !rate->count)
> -		return 0;
> +		return -1;
>   
>   	if (rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH)
> -		stat.bw = RATE_INFO_BW_80;
> +		stat->bw = RATE_INFO_BW_80;
>   	else if (rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
> -		stat.bw = RATE_INFO_BW_40;
> +		stat->bw = RATE_INFO_BW_40;
>   	else
> -		stat.bw = RATE_INFO_BW_20;
> +		stat->bw = RATE_INFO_BW_20;

hint:

--- airtime.c
+++ airtime.c
@@ -560,7 +560,9 @@
         if (rate->idx < 0 || !rate->count)
                 return -1;

-       if (rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH)
+       if (rate->flags & IEEE80211_TX_RC_160_MHZ_WIDTH)
+               stat->bw = RATE_INFO_BW_160;
+       else if (rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH)
                 stat->bw = RATE_INFO_BW_80;
         else if (rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
                 stat->bw = RATE_INFO_BW_40;

>   
> -	stat.enc_flags = 0;
> +	stat->enc_flags = 0;
>   	if (rate->flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
> -		stat.enc_flags |= RX_ENC_FLAG_SHORTPRE;
> +		stat->enc_flags |= RX_ENC_FLAG_SHORTPRE;
>   	if (rate->flags & IEEE80211_TX_RC_SHORT_GI)
> -		stat.enc_flags |= RX_ENC_FLAG_SHORT_GI;
> +		stat->enc_flags |= RX_ENC_FLAG_SHORT_GI;
>   
> -	stat.rate_idx = rate->idx;
> +	stat->rate_idx = rate->idx;
>   	if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
> -		stat.encoding = RX_ENC_VHT;
> -		stat.rate_idx = ieee80211_rate_get_vht_mcs(rate);
> -		stat.nss = ieee80211_rate_get_vht_nss(rate);
> +		stat->encoding = RX_ENC_VHT;
> +		stat->rate_idx = ieee80211_rate_get_vht_mcs(rate);
> +		stat->nss = ieee80211_rate_get_vht_nss(rate);
>   	} else if (rate->flags & IEEE80211_TX_RC_MCS) {
> -		stat.encoding = RX_ENC_HT;
> +		stat->encoding = RX_ENC_HT;
>   	} else {
> -		stat.encoding = RX_ENC_LEGACY;
> +		stat->encoding = RX_ENC_LEGACY;
>   	}
>   
> -out:
> +	return 0;
> +}
> +
> +static u32 ieee80211_calc_tx_airtime_rate(struct ieee80211_hw *hw,
> +					  struct ieee80211_tx_rate *rate,
> +					  struct rate_info *ri,
> +					  u8 band, int len)
> +{
> +	struct ieee80211_rx_status stat;
> +
> +	if (ieee80211_fill_rx_status(&stat, hw, rate, ri, band, len))
> +		return 0;
> +
>   	return ieee80211_calc_rx_airtime(hw, &stat, len);
>   }
>