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freebsd-dev/sys/dev/ath/if_ath_tx_ht.c
Adrian Chadd cce6344402 [ath] [ath_rate] Extend ath_rate_sample to better handle 11n rates and aggregates. 
My initial rate control code was .. suboptimal.  I wanted to at least get MCS
rates sent, but it didn't do anywhere near enough to handle low signal level links
or remotely keep accurate statistics.

So, 8 years later, here's what I should've done back then.

* Firstly, I wasn't at all tracking packet sizes other than the two buckets
  (250 and 1600 bytes.)  So, extend it to include 4096, 8192, 16384, 32768 and
  65536.  I may go add 2048 at some point if I find it's useful.

  This is important for a few reasons.  First, when forming A-MPDU or AMSDU
  aggregates the frame sizes are larger, and thus the TX time calculation
  is woefully, increasingly wrong.  Secondly, the behaviour of 802.11 channels
  isn't some fixed thing, both due to channel conditions and radios themselves.
  Notably, there was some observations done a few years ago on 11n chipsets
  which noticed longer aggregates showed an increase in failed A-MPDU sub-frame
  reception as you got further along in the transmit time.  It could be due to
  a variety of things - transmitter linearity, channel conditions changing,
  frequency/phase drift, etc - but the observation was to potentially form
  shorter aggregates to improve BER.

* .. and then modify the ath TX path to report the length of the aggregate sent,
  so as the statistics kept would line up with the correct bucket.

* Then on the rate control look-up side - i was also only using the first frame
  length for an A-MPDU rate control lookup which isn't good enough here.
  So, add a new method that walks the TID software queue for that node to
  find out what the likely length of data available is.  It isn't ALL of the
  data in the queue because we'll only ever send enough data to fit inside the
  block-ack window, so limit how many bytes we return to roughly what ath_tx_form_aggr()
  would do.

* .. and cache that in the first ath_buf in the aggregate so it and the eventual
  AMPDU length can be returned to the rate control code.

* THEN, modify the rate control code to look at them both when deciding which bucket
  to attribute the sent frame on.  I'm erring on the side of caution and using the
  size bucket that the lookup is based on.

Ok, so now the rate lookups and statistics are "more correct".  However, MCS rates
are not the same as 11abg rates in that they're not a monotonically incrementing
set of faster rates and you can't assume that just because a given MCS rate fails,
the next higher one wouldn't work better or be a lower average tx time.

So, I had to do a bunch of surgery to the best rate and sample rate math.
This is the bit that's a WIP.

* First, simplify the statistics updates (update_stats()) to do a single pass on
  all rates.
* Next, make sure that each rate average tx time is updated based on /its/ failure/success.
  Eg if you sent a frame with { MCS15, MCS12, MCS8 } and MCS8 succeeded, MCS15 and MCS
  12 would have their average tx time updated for /their/ part of the transmission,
  not the whole transmission.
* Next, EWMA wasn't being fully calculated based on the /failures/ in each of the
  rate attempts.  So, if MCS15, MCS12 failed above but MCS8 didn't, then ensure
  that the statistics noted that /all/ subframes failed at those rates, rather than
  the eventual set of transmitted/sent frames.   This ensures the EWMA /and/ average
  TX time are updated correctly.
* When picking a sample rate and initial rate, probe rates aroud the current MCS
  but limit it to MCS0..7 /for all spatial streams/, rather than doing crazy things
  like hitting MCS7 and then probing MCS8 - MCS8 is basically MCS0 but two spatial
  streams.  It's a /lot/ slower than MCS7.  Also, the reverse is true - if we're at
  MCS8 then don't probe MCS7 as part of it, it's not likely to succeed.
* Fix bugs in pick_best_rate() where I was /immediately/ choosing the highest MCS
  rate if there weren't any frames yet transmitted.  I was defaulting to 25% EWMA and
  .. then each comparison would accept the higher rate.  Just skip those; sampling
  will fill in the details.

So, this seems to work a lot better.  It's not perfect; I'm still seeing a lot of
instability around higher MCS rates because there are bursts of loss/retransmissions
that aren't /too/ bad.  But i'll keep iterating over this and tidying up my hacks.

Ok, so why this still something I'm poking at? rather than porting minstrel_ht?

ath_rate_sample tries to minimise airtime, not maximise throughput.  I have
extended it with an EWMA based on sub-frame success/failures - high MCS rates
that have partially successful receptions still show super short average frame
times, but a /lot/ of retransmits have to happen for that to work.
So for MCS rates I also track this EWMA and ensure that the rates I'm choosing
don't have super crappy packet failures.  I don't mind not getting lower
peak throughput versus minstrel_ht; instead I want to see if I can make "minimise
airtime" work well.

Tested:

* AR9380, STA mode
* AR9344, STA mode
* AR9580, STA/AP mode
2020-05-15 18:51:20 +00:00

1047 lines
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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2011 Adrian Chadd, Xenion Pty Ltd.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
* redistribution must be conditioned upon including a substantially
* similar Disclaimer requirement for further binary redistribution.
*
* NO WARRANTY
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGES.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_ath.h"
#include "opt_wlan.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/errno.h>
#include <sys/callout.h>
#include <sys/bus.h>
#include <sys/endian.h>
#include <sys/kthread.h>
#include <sys/taskqueue.h>
#include <sys/priv.h>
#include <machine/bus.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_types.h>
#include <net/if_arp.h>
#include <net/ethernet.h>
#include <net/if_llc.h>
#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_regdomain.h>
#ifdef IEEE80211_SUPPORT_SUPERG
#include <net80211/ieee80211_superg.h>
#endif
#ifdef IEEE80211_SUPPORT_TDMA
#include <net80211/ieee80211_tdma.h>
#endif
#include <net/bpf.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif
#include <dev/ath/if_athvar.h>
#include <dev/ath/ath_hal/ah_devid.h> /* XXX for softled */
#include <dev/ath/ath_hal/ah_diagcodes.h>
#ifdef ATH_TX99_DIAG
#include <dev/ath/ath_tx99/ath_tx99.h>
#endif
#include <dev/ath/if_ath_tx.h> /* XXX for some support functions */
#include <dev/ath/if_ath_tx_ht.h>
#include <dev/ath/if_athrate.h>
#include <dev/ath/if_ath_debug.h>
/*
* XXX net80211?
*/
#define IEEE80211_AMPDU_SUBFRAME_DEFAULT 32
#define ATH_AGGR_DELIM_SZ 4 /* delimiter size */
#define ATH_AGGR_MINPLEN 256 /* in bytes, minimum packet length */
/* number of delimiters for encryption padding */
#define ATH_AGGR_ENCRYPTDELIM 10
/*
* returns delimiter padding required given the packet length
*/
#define ATH_AGGR_GET_NDELIM(_len) \
(((((_len) + ATH_AGGR_DELIM_SZ) < ATH_AGGR_MINPLEN) ? \
(ATH_AGGR_MINPLEN - (_len) - ATH_AGGR_DELIM_SZ) : 0) >> 2)
#define PADBYTES(_len) ((4 - ((_len) % 4)) % 4)
int ath_max_4ms_framelen[4][32] = {
[MCS_HT20] = {
3212, 6432, 9648, 12864, 19300, 25736, 28952, 32172,
6424, 12852, 19280, 25708, 38568, 51424, 57852, 64280,
9628, 19260, 28896, 38528, 57792, 65532, 65532, 65532,
12828, 25656, 38488, 51320, 65532, 65532, 65532, 65532,
},
[MCS_HT20_SGI] = {
3572, 7144, 10720, 14296, 21444, 28596, 32172, 35744,
7140, 14284, 21428, 28568, 42856, 57144, 64288, 65532,
10700, 21408, 32112, 42816, 64228, 65532, 65532, 65532,
14256, 28516, 42780, 57040, 65532, 65532, 65532, 65532,
},
[MCS_HT40] = {
6680, 13360, 20044, 26724, 40092, 53456, 60140, 65532,
13348, 26700, 40052, 53400, 65532, 65532, 65532, 65532,
20004, 40008, 60016, 65532, 65532, 65532, 65532, 65532,
26644, 53292, 65532, 65532, 65532, 65532, 65532, 65532,
},
[MCS_HT40_SGI] = {
7420, 14844, 22272, 29696, 44544, 59396, 65532, 65532,
14832, 29668, 44504, 59340, 65532, 65532, 65532, 65532,
22232, 44464, 65532, 65532, 65532, 65532, 65532, 65532,
29616, 59232, 65532, 65532, 65532, 65532, 65532, 65532,
}
};
/*
* XXX should be in net80211
*/
static int ieee80211_mpdudensity_map[] = {
0, /* IEEE80211_HTCAP_MPDUDENSITY_NA */
25, /* IEEE80211_HTCAP_MPDUDENSITY_025 */
50, /* IEEE80211_HTCAP_MPDUDENSITY_05 */
100, /* IEEE80211_HTCAP_MPDUDENSITY_1 */
200, /* IEEE80211_HTCAP_MPDUDENSITY_2 */
400, /* IEEE80211_HTCAP_MPDUDENSITY_4 */
800, /* IEEE80211_HTCAP_MPDUDENSITY_8 */
1600, /* IEEE80211_HTCAP_MPDUDENSITY_16 */
};
/*
* XXX should be in the HAL/net80211 ?
*/
#define BITS_PER_BYTE 8
#define OFDM_PLCP_BITS 22
#define HT_RC_2_MCS(_rc) ((_rc) & 0x7f)
#define HT_RC_2_STREAMS(_rc) ((((_rc) & 0x78) >> 3) + 1)
#define L_STF 8
#define L_LTF 8
#define L_SIG 4
#define HT_SIG 8
#define HT_STF 4
#define HT_LTF(_ns) (4 * (_ns))
#define SYMBOL_TIME(_ns) ((_ns) << 2) // ns * 4 us
#define SYMBOL_TIME_HALFGI(_ns) (((_ns) * 18 + 4) / 5) // ns * 3.6 us
#define NUM_SYMBOLS_PER_USEC(_usec) (_usec >> 2)
#define NUM_SYMBOLS_PER_USEC_HALFGI(_usec) (((_usec*5)-4)/18)
#define IS_HT_RATE(_rate) ((_rate) & 0x80)
const uint32_t bits_per_symbol[][2] = {
/* 20MHz 40MHz */
{ 26, 54 }, // 0: BPSK
{ 52, 108 }, // 1: QPSK 1/2
{ 78, 162 }, // 2: QPSK 3/4
{ 104, 216 }, // 3: 16-QAM 1/2
{ 156, 324 }, // 4: 16-QAM 3/4
{ 208, 432 }, // 5: 64-QAM 2/3
{ 234, 486 }, // 6: 64-QAM 3/4
{ 260, 540 }, // 7: 64-QAM 5/6
{ 52, 108 }, // 8: BPSK
{ 104, 216 }, // 9: QPSK 1/2
{ 156, 324 }, // 10: QPSK 3/4
{ 208, 432 }, // 11: 16-QAM 1/2
{ 312, 648 }, // 12: 16-QAM 3/4
{ 416, 864 }, // 13: 64-QAM 2/3
{ 468, 972 }, // 14: 64-QAM 3/4
{ 520, 1080 }, // 15: 64-QAM 5/6
{ 78, 162 }, // 16: BPSK
{ 156, 324 }, // 17: QPSK 1/2
{ 234, 486 }, // 18: QPSK 3/4
{ 312, 648 }, // 19: 16-QAM 1/2
{ 468, 972 }, // 20: 16-QAM 3/4
{ 624, 1296 }, // 21: 64-QAM 2/3
{ 702, 1458 }, // 22: 64-QAM 3/4
{ 780, 1620 }, // 23: 64-QAM 5/6
{ 104, 216 }, // 24: BPSK
{ 208, 432 }, // 25: QPSK 1/2
{ 312, 648 }, // 26: QPSK 3/4
{ 416, 864 }, // 27: 16-QAM 1/2
{ 624, 1296 }, // 28: 16-QAM 3/4
{ 832, 1728 }, // 29: 64-QAM 2/3
{ 936, 1944 }, // 30: 64-QAM 3/4
{ 1040, 2160 }, // 31: 64-QAM 5/6
};
/*
* Fill in the rate array information based on the current
* node configuration and the choices made by the rate
* selection code and ath_buf setup code.
*
* Later on, this may end up also being made by the
* rate control code, but for now it can live here.
*
* This needs to be called just before the packet is
* queued to the software queue or hardware queue,
* so all of the needed fields in bf_state are setup.
*/
void
ath_tx_rate_fill_rcflags(struct ath_softc *sc, struct ath_buf *bf)
{
struct ieee80211_node *ni = bf->bf_node;
struct ieee80211vap *vap = ni->ni_vap;
struct ieee80211com *ic = ni->ni_ic;
const HAL_RATE_TABLE *rt = sc->sc_currates;
struct ath_rc_series *rc = bf->bf_state.bfs_rc;
uint8_t rate;
int i;
int do_ldpc;
int do_stbc;
/*
* We only do LDPC if the rate is 11n, both we and the
* receiver support LDPC and it's enabled.
*
* It's a global flag, not a per-try flag, so we clear
* it if any of the rate entries aren't 11n.
*/
do_ldpc = 0;
if ((ni->ni_vap->iv_flags_ht & IEEE80211_FHT_LDPC_TX) &&
(ni->ni_htcap & IEEE80211_HTCAP_LDPC))
do_ldpc = 1;
/*
* The 11n duration calculation doesn't know about LDPC,
* so don't enable it for positioning.
*/
if (bf->bf_flags & ATH_BUF_TOA_PROBE)
do_ldpc = 0;
do_stbc = 0;
for (i = 0; i < ATH_RC_NUM; i++) {
rc[i].flags = 0;
if (rc[i].tries == 0)
continue;
rate = rt->info[rc[i].rix].rateCode;
/*
* Only enable short preamble for legacy rates
*/
if ((! IS_HT_RATE(rate)) && bf->bf_state.bfs_shpream)
rate |= rt->info[rc[i].rix].shortPreamble;
/*
* Save this, used by the TX and completion code
*/
rc[i].ratecode = rate;
if (bf->bf_state.bfs_txflags &
(HAL_TXDESC_RTSENA | HAL_TXDESC_CTSENA))
rc[i].flags |= ATH_RC_RTSCTS_FLAG;
/*
* If we can't do LDPC, don't.
*/
if (! IS_HT_RATE(rate))
do_ldpc = 0;
/* Only enable shortgi, 2040, dual-stream if HT is set */
if (IS_HT_RATE(rate)) {
rc[i].flags |= ATH_RC_HT_FLAG;
if (ni->ni_chw == 40)
rc[i].flags |= ATH_RC_CW40_FLAG;
/*
* NOTE: Don't do short-gi for positioning frames.
*
* For now, the ath_hal and net80211 HT duration
* calculation rounds up the 11n data txtime
* to the nearest multiple of 3.6 microseconds
* and doesn't return the fractional part, so
* we are always "out" by some amount.
*/
if (ni->ni_chw == 40 &&
ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40 &&
ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40 &&
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40 &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_SGI_FLAG;
}
if (ni->ni_chw == 20 &&
ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20 &&
ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20 &&
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20 &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_SGI_FLAG;
}
/*
* If we have STBC TX enabled and the receiver
* can receive (at least) 1 stream STBC, AND it's
* MCS 0-7, AND we have at least two chains enabled,
* and we're not doing positioning, enable STBC.
*/
if (ic->ic_htcaps & IEEE80211_HTCAP_TXSTBC &&
(ni->ni_vap->iv_flags_ht & IEEE80211_FHT_STBC_TX) &&
(ni->ni_htcap & IEEE80211_HTCAP_RXSTBC) &&
(sc->sc_cur_txchainmask > 1) &&
(HT_RC_2_STREAMS(rate) == 1) &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_STBC_FLAG;
do_stbc = 1;
}
/*
* Dual / Triple stream rate?
*/
if (HT_RC_2_STREAMS(rate) == 2)
rc[i].flags |= ATH_RC_DS_FLAG;
else if (HT_RC_2_STREAMS(rate) == 3)
rc[i].flags |= ATH_RC_TS_FLAG;
}
/*
* Calculate the maximum TX power cap for the current
* node.
*/
rc[i].tx_power_cap = ieee80211_get_node_txpower(ni);
/*
* Calculate the maximum 4ms frame length based
* on the MCS rate, SGI and channel width flags.
*/
if ((rc[i].flags & ATH_RC_HT_FLAG) &&
(HT_RC_2_MCS(rate) < 32)) {
int j;
if (rc[i].flags & ATH_RC_CW40_FLAG) {
if (rc[i].flags & ATH_RC_SGI_FLAG)
j = MCS_HT40_SGI;
else
j = MCS_HT40;
} else {
if (rc[i].flags & ATH_RC_SGI_FLAG)
j = MCS_HT20_SGI;
else
j = MCS_HT20;
}
rc[i].max4msframelen =
ath_max_4ms_framelen[j][HT_RC_2_MCS(rate)];
} else
rc[i].max4msframelen = 0;
DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
"%s: i=%d, rate=0x%x, flags=0x%x, max4ms=%d\n",
__func__, i, rate, rc[i].flags, rc[i].max4msframelen);
}
/*
* LDPC is a global flag, so ...
*/
if (do_ldpc) {
bf->bf_state.bfs_txflags |= HAL_TXDESC_LDPC;
sc->sc_stats.ast_tx_ldpc++;
}
if (do_stbc) {
sc->sc_stats.ast_tx_stbc++;
}
}
/*
* Return the number of delimiters to be added to
* meet the minimum required mpdudensity.
*
* Caller should make sure that the rate is HT.
*
* TODO: is this delimiter calculation supposed to be the
* total frame length, the hdr length, the data length (including
* delimiters, padding, CRC, etc) or ?
*
* TODO: this should ensure that the rate control information
* HAS been setup for the first rate.
*
* TODO: ensure this is only called for MCS rates.
*
* TODO: enforce MCS < 31
*/
static int
ath_compute_num_delims(struct ath_softc *sc, struct ath_buf *first_bf,
uint16_t pktlen, int is_first)
{
#define MS(_v, _f) (((_v) & _f) >> _f##_S)
const HAL_RATE_TABLE *rt = sc->sc_currates;
struct ieee80211_node *ni = first_bf->bf_node;
struct ieee80211vap *vap = ni->ni_vap;
int ndelim, mindelim = 0;
int mpdudensity; /* in 1/100'th of a microsecond */
int peer_mpdudensity; /* net80211 value */
uint8_t rc, rix, flags;
int width, half_gi;
uint32_t nsymbits, nsymbols;
uint16_t minlen;
/*
* Get the advertised density from the node.
*/
peer_mpdudensity = MS(ni->ni_htparam, IEEE80211_HTCAP_MPDUDENSITY);
/*
* vap->iv_ampdu_density is a net80211 value, rather than the actual
* density. Larger values are longer A-MPDU density spacing values,
* and we want to obey larger configured / negotiated density values
* per station if we get it.
*/
if (vap->iv_ampdu_density > peer_mpdudensity)
peer_mpdudensity = vap->iv_ampdu_density;
/*
* Convert the A-MPDU density net80211 value to a 1/100 microsecond
* value for subsequent calculations.
*/
if (peer_mpdudensity > IEEE80211_HTCAP_MPDUDENSITY_16)
mpdudensity = 1600; /* maximum density */
else
mpdudensity = ieee80211_mpdudensity_map[peer_mpdudensity];
/* Select standard number of delimiters based on frame length */
ndelim = ATH_AGGR_GET_NDELIM(pktlen);
/*
* If encryption is enabled, add extra delimiters to let the
* crypto hardware catch up. This could be tuned per-MAC and
* per-rate, but for now we'll simply assume encryption is
* always enabled.
*
* Also note that the Atheros reference driver inserts two
* delimiters by default for pre-AR9380 peers. This will
* include "that" required delimiter.
*/
ndelim += ATH_AGGR_ENCRYPTDELIM;
/*
* For AR9380, there's a minimum number of delimeters
* required when doing RTS.
*
* XXX TODO: this is only needed if (a) RTS/CTS is enabled for
* this exchange, and (b) (done) this is the first sub-frame
* in the aggregate.
*/
if (sc->sc_use_ent && (sc->sc_ent_cfg & AH_ENT_RTSCTS_DELIM_WAR)
&& ndelim < AH_FIRST_DESC_NDELIMS && is_first)
ndelim = AH_FIRST_DESC_NDELIMS;
/*
* If sc_delim_min_pad is non-zero, enforce it as the minimum
* pad delimiter count.
*/
if (sc->sc_delim_min_pad != 0)
ndelim = MAX(ndelim, sc->sc_delim_min_pad);
DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
"%s: pktlen=%d, ndelim=%d, mpdudensity=%d\n",
__func__, pktlen, ndelim, mpdudensity);
/*
* If the MPDU density is 0, we can return here.
* Otherwise, we need to convert the desired mpdudensity
* into a byte length, based on the rate in the subframe.
*/
if (mpdudensity == 0)
return ndelim;
/*
* Convert desired mpdu density from microeconds to bytes based
* on highest rate in rate series (i.e. first rate) to determine
* required minimum length for subframe. Take into account
* whether high rate is 20 or 40Mhz and half or full GI.
*/
rix = first_bf->bf_state.bfs_rc[0].rix;
rc = rt->info[rix].rateCode;
flags = first_bf->bf_state.bfs_rc[0].flags;
width = !! (flags & ATH_RC_CW40_FLAG);
half_gi = !! (flags & ATH_RC_SGI_FLAG);
/*
* mpdudensity is in 1/100th of a usec, so divide by 100
*/
if (half_gi)
nsymbols = NUM_SYMBOLS_PER_USEC_HALFGI(mpdudensity);
else
nsymbols = NUM_SYMBOLS_PER_USEC(mpdudensity);
nsymbols /= 100;
if (nsymbols == 0)
nsymbols = 1;
nsymbits = bits_per_symbol[HT_RC_2_MCS(rc)][width];
minlen = (nsymbols * nsymbits) / BITS_PER_BYTE;
/*
* Min length is the minimum frame length for the
* required MPDU density.
*/
if (pktlen < minlen) {
mindelim = (minlen - pktlen) / ATH_AGGR_DELIM_SZ;
ndelim = MAX(mindelim, ndelim);
}
DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
"%s: pktlen=%d, minlen=%d, rix=%x, rc=%x, width=%d, hgi=%d, ndelim=%d\n",
__func__, pktlen, minlen, rix, rc, width, half_gi, ndelim);
return ndelim;
#undef MS
}
/*
* XXX TODO: put into net80211
*/
static int
ath_rx_ampdu_to_byte(char a)
{
switch (a) {
case IEEE80211_HTCAP_MAXRXAMPDU_16K:
return 16384;
break;
case IEEE80211_HTCAP_MAXRXAMPDU_32K:
return 32768;
break;
case IEEE80211_HTCAP_MAXRXAMPDU_64K:
return 65536;
break;
case IEEE80211_HTCAP_MAXRXAMPDU_8K:
default:
return 8192;
break;
}
}
/*
* Fetch the aggregation limit.
*
* It's the lowest of the four rate series 4ms frame length.
*
* Also take into account the hardware specific limits (8KiB on AR5416)
* and per-peer limits in non-STA mode.
*/
static int
ath_get_aggr_limit(struct ath_softc *sc, struct ieee80211_node *ni,
struct ath_buf *bf)
{
struct ieee80211vap *vap = ni->ni_vap;
#define MS(_v, _f) (((_v) & _f) >> _f##_S)
int amin = ATH_AGGR_MAXSIZE;
int i;
/* Extract out the maximum configured driver A-MPDU limit */
if (sc->sc_aggr_limit > 0 && sc->sc_aggr_limit < ATH_AGGR_MAXSIZE)
amin = sc->sc_aggr_limit;
/* Check the vap configured transmit limit */
amin = MIN(amin, ath_rx_ampdu_to_byte(vap->iv_ampdu_limit));
/*
* Check the HTCAP field for the maximum size the node has
* negotiated. If it's smaller than what we have, cap it there.
*/
amin = MIN(amin, ath_rx_ampdu_to_byte(MS(ni->ni_htparam,
IEEE80211_HTCAP_MAXRXAMPDU)));
for (i = 0; i < ATH_RC_NUM; i++) {
if (bf->bf_state.bfs_rc[i].tries == 0)
continue;
amin = MIN(amin, bf->bf_state.bfs_rc[i].max4msframelen);
}
DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
"%s: aggr_limit=%d, iv_ampdu_limit=%d, "
"peer maxrxampdu=%d, max frame len=%d\n",
__func__,
sc->sc_aggr_limit,
vap->iv_ampdu_limit,
MS(ni->ni_htparam, IEEE80211_HTCAP_MAXRXAMPDU),
amin);
return amin;
#undef MS
}
/*
* Setup a 11n rate series structure
*
* This should be called for both legacy and MCS rates.
*
* This uses the rate series stuf from ath_tx_rate_fill_rcflags().
*
* It, along with ath_buf_set_rate, must be called -after- a burst
* or aggregate is setup.
*/
static void
ath_rateseries_setup(struct ath_softc *sc, struct ieee80211_node *ni,
struct ath_buf *bf, HAL_11N_RATE_SERIES *series)
{
struct ieee80211com *ic = ni->ni_ic;
struct ath_hal *ah = sc->sc_ah;
HAL_BOOL shortPreamble = AH_FALSE;
const HAL_RATE_TABLE *rt = sc->sc_currates;
int i;
int pktlen;
struct ath_rc_series *rc = bf->bf_state.bfs_rc;
if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
(ni->ni_capinfo & IEEE80211_CAPINFO_SHORT_PREAMBLE))
shortPreamble = AH_TRUE;
/*
* If this is the first frame in an aggregate series,
* use the aggregate length.
*/
if (bf->bf_state.bfs_aggr)
pktlen = bf->bf_state.bfs_al;
else
pktlen = bf->bf_state.bfs_pktlen;
/*
* XXX TODO: modify this routine to use the bfs_rc[x].flags
* XXX fields.
*/
memset(series, 0, sizeof(HAL_11N_RATE_SERIES) * 4);
for (i = 0; i < ATH_RC_NUM; i++) {
/* Only set flags for actual TX attempts */
if (rc[i].tries == 0)
continue;
series[i].Tries = rc[i].tries;
/*
* XXX TODO: When the NIC is capable of three stream TX,
* transmit 1/2 stream rates on two streams.
*
* This reduces the power consumption of the NIC and
* keeps it within the PCIe slot power limits.
*/
series[i].ChSel = sc->sc_cur_txchainmask;
/*
* Setup rate and TX power cap for this series.
*/
series[i].Rate = rt->info[rc[i].rix].rateCode;
series[i].RateIndex = rc[i].rix;
series[i].tx_power_cap = rc[i].tx_power_cap;
/*
* Enable RTS/CTS as appropriate.
*/
if (rc[i].flags & ATH_RC_RTSCTS_FLAG)
series[i].RateFlags |= HAL_RATESERIES_RTS_CTS;
/*
* 11n rate? Update 11n flags.
*/
if (rc[i].flags & ATH_RC_HT_FLAG) {
if (rc[i].flags & ATH_RC_CW40_FLAG)
series[i].RateFlags |= HAL_RATESERIES_2040;
if (rc[i].flags & ATH_RC_SGI_FLAG)
series[i].RateFlags |= HAL_RATESERIES_HALFGI;
if (rc[i].flags & ATH_RC_STBC_FLAG)
series[i].RateFlags |= HAL_RATESERIES_STBC;
}
/*
* TODO: If we're all doing 11n rates then we can set LDPC.
* If we've been asked to /do/ LDPC but we are handed a
* legacy rate, then we should complain. Loudly.
*/
/*
* PktDuration doesn't include slot, ACK, RTS, etc timing -
* it's just the packet duration
*/
if (rc[i].flags & ATH_RC_HT_FLAG) {
series[i].PktDuration =
ath_computedur_ht(pktlen
, series[i].Rate
, HT_RC_2_STREAMS(series[i].Rate)
, series[i].RateFlags & HAL_RATESERIES_2040
, series[i].RateFlags & HAL_RATESERIES_HALFGI);
} else {
if (shortPreamble)
series[i].Rate |=
rt->info[rc[i].rix].shortPreamble;
/* XXX TODO: don't include SIFS */
series[i].PktDuration = ath_hal_computetxtime(ah,
rt, pktlen, rc[i].rix, shortPreamble, AH_TRUE);
}
}
}
#ifdef ATH_DEBUG
static void
ath_rateseries_print(struct ath_softc *sc, HAL_11N_RATE_SERIES *series)
{
int i;
for (i = 0; i < ATH_RC_NUM; i++) {
device_printf(sc->sc_dev ,"series %d: rate %x; tries %d; "
"pktDuration %d; chSel %d; txpowcap %d, rateFlags %x\n",
i,
series[i].Rate,
series[i].Tries,
series[i].PktDuration,
series[i].ChSel,
series[i].tx_power_cap,
series[i].RateFlags);
}
}
#endif
/*
* Setup the 11n rate scenario and burst duration for the given TX descriptor
* list.
*
* This isn't useful for sending beacon frames, which has different needs
* wrt what's passed into the rate scenario function.
*/
void
ath_buf_set_rate(struct ath_softc *sc, struct ieee80211_node *ni,
struct ath_buf *bf)
{
HAL_11N_RATE_SERIES series[4];
struct ath_desc *ds = bf->bf_desc;
struct ath_hal *ah = sc->sc_ah;
int is_pspoll = (bf->bf_state.bfs_atype == HAL_PKT_TYPE_PSPOLL);
int ctsrate = bf->bf_state.bfs_ctsrate;
int flags = bf->bf_state.bfs_txflags;
/* Setup rate scenario */
memset(&series, 0, sizeof(series));
ath_rateseries_setup(sc, ni, bf, series);
#ifdef ATH_DEBUG
if (sc->sc_debug & ATH_DEBUG_XMIT)
ath_rateseries_print(sc, series);
#endif
/* Set rate scenario */
/*
* Note: Don't allow hardware to override the duration on
* ps-poll packets.
*/
ath_hal_set11nratescenario(ah, ds,
!is_pspoll, /* whether to override the duration or not */
ctsrate, /* rts/cts rate */
series, /* 11n rate series */
4, /* number of series */
flags);
/* Set burst duration */
/*
* This is only required when doing 11n burst, not aggregation
* ie, if there's a second frame in a RIFS or A-MPDU burst
* w/ >1 A-MPDU frame bursting back to back.
* Normal A-MPDU doesn't do bursting -between- aggregates.
*
* .. and it's highly likely this won't ever be implemented
*/
//ath_hal_set11nburstduration(ah, ds, 8192);
}
/*
* Form an aggregate packet list.
*
* This function enforces the aggregate restrictions/requirements.
*
* These are:
*
* + The aggregate size maximum (64k for AR9160 and later, 8K for
* AR5416 when doing RTS frame protection.)
* + Maximum number of sub-frames for an aggregate
* + The aggregate delimiter size, giving MACs time to do whatever is
* needed before each frame
* + Enforce the BAW limit
*
* Each descriptor queued should have the DMA setup.
* The rate series, descriptor setup, linking, etc is all done
* externally. This routine simply chains them together.
* ath_tx_setds_11n() will take care of configuring the per-
* descriptor setup, and ath_buf_set_rate() will configure the
* rate control.
*
* The TID lock is required for the entirety of this function.
*
* If some code in another thread adds to the head of this
* list, very strange behaviour will occur. Since retransmission is the
* only reason this will occur, and this routine is designed to be called
* from within the scheduler task, it won't ever clash with the completion
* task.
*
* So if you want to call this from an upper layer context (eg, to direct-
* dispatch aggregate frames to the hardware), please keep this in mind.
*/
ATH_AGGR_STATUS
ath_tx_form_aggr(struct ath_softc *sc, struct ath_node *an,
struct ath_tid *tid, ath_bufhead *bf_q)
{
//struct ieee80211_node *ni = &an->an_node;
struct ath_buf *bf, *bf_first = NULL, *bf_prev = NULL;
int nframes = 0;
uint16_t aggr_limit = 0, al = 0, bpad = 0, al_delta, h_baw;
struct ieee80211_tx_ampdu *tap;
int status = ATH_AGGR_DONE;
int prev_frames = 0; /* XXX for AR5416 burst, not done here */
int prev_al = 0; /* XXX also for AR5416 burst */
ATH_TX_LOCK_ASSERT(sc);
tap = ath_tx_get_tx_tid(an, tid->tid);
if (tap == NULL) {
status = ATH_AGGR_ERROR;
goto finish;
}
/*
* Limit the maximum number of frames in this A-MPDU
* to half of the window size. This is done to prevent
* sending a LOT of frames that may fail in one batch
* when operating in higher MCS rates. If there are more
* frames available to send then up to two A-MPDUs will
* be queued per hardware queue, so we'll "just" get
* a second A-MPDU.
*/
h_baw = tap->txa_wnd / 2;
for (;;) {
bf = ATH_TID_FIRST(tid);
if (bf == NULL) {
status = ATH_AGGR_DONE;
break;
}
if (bf_first == NULL) {
bf_first = bf;
/*
* It's the first frame;
* set the aggregation limit based on the
* rate control decision that has been made.
*/
aggr_limit = ath_get_aggr_limit(sc, &an->an_node,
bf_first);
if (bf_first->bf_state.bfs_rc_maxpktlen > 0) {
aggr_limit = MIN(aggr_limit,
bf_first->bf_state.bfs_rc_maxpktlen);
}
}
/* Set this early just so things don't get confused */
bf->bf_next = NULL;
/*
* If the frame doesn't have a sequence number that we're
* tracking in the BAW (eg NULL QOS data frame), we can't
* aggregate it. Stop the aggregation process; the sender
* can then TX what's in the list thus far and then
* TX the frame individually.
*/
if (! bf->bf_state.bfs_dobaw) {
status = ATH_AGGR_NONAGGR;
break;
}
/*
* If any of the rates are non-HT, this packet
* can't be aggregated.
* XXX TODO: add a bf_state flag which gets marked
* if any active rate is non-HT.
*/
/*
* do not exceed aggregation limit
*/
al_delta = ATH_AGGR_DELIM_SZ + bf->bf_state.bfs_pktlen;
if (nframes &&
(aggr_limit < (al + bpad + al_delta + prev_al))) {
status = ATH_AGGR_LIMITED;
break;
}
/*
* If RTS/CTS is set on the first frame, enforce
* the RTS aggregate limit.
*/
if (bf_first->bf_state.bfs_txflags &
(HAL_TXDESC_CTSENA | HAL_TXDESC_RTSENA)) {
if (nframes &&
(sc->sc_rts_aggr_limit <
(al + bpad + al_delta + prev_al))) {
status = ATH_AGGR_8K_LIMITED;
break;
}
}
/*
* Do not exceed subframe limit.
*/
if ((nframes + prev_frames) >= MIN((h_baw),
IEEE80211_AMPDU_SUBFRAME_DEFAULT)) {
status = ATH_AGGR_LIMITED;
break;
}
/*
* If the current frame has an RTS/CTS configuration
* that differs from the first frame, override the
* subsequent frame with this config.
*/
if (bf != bf_first) {
bf->bf_state.bfs_txflags &=
~ (HAL_TXDESC_RTSENA | HAL_TXDESC_CTSENA);
bf->bf_state.bfs_txflags |=
bf_first->bf_state.bfs_txflags &
(HAL_TXDESC_RTSENA | HAL_TXDESC_CTSENA);
}
/*
* If the packet has a sequence number, do not
* step outside of the block-ack window.
*/
if (! BAW_WITHIN(tap->txa_start, tap->txa_wnd,
SEQNO(bf->bf_state.bfs_seqno))) {
status = ATH_AGGR_BAW_CLOSED;
break;
}
/*
* this packet is part of an aggregate.
*/
ATH_TID_REMOVE(tid, bf, bf_list);
/* The TID lock is required for the BAW update */
ath_tx_addto_baw(sc, an, tid, bf);
bf->bf_state.bfs_addedbaw = 1;
/*
* XXX enforce ACK for aggregate frames (this needs to be
* XXX handled more gracefully?
*/
if (bf->bf_state.bfs_txflags & HAL_TXDESC_NOACK) {
device_printf(sc->sc_dev,
"%s: HAL_TXDESC_NOACK set for an aggregate frame?\n",
__func__);
bf->bf_state.bfs_txflags &= (~HAL_TXDESC_NOACK);
}
/*
* Add the now owned buffer (which isn't
* on the software TXQ any longer) to our
* aggregate frame list.
*/
TAILQ_INSERT_TAIL(bf_q, bf, bf_list);
nframes ++;
/* Completion handler */
bf->bf_comp = ath_tx_aggr_comp;
/*
* add padding for previous frame to aggregation length
*/
al += bpad + al_delta;
/*
* Calculate delimiters needed for the current frame
*/
bf->bf_state.bfs_ndelim =
ath_compute_num_delims(sc, bf_first,
bf->bf_state.bfs_pktlen, (bf_first == bf));
/*
* Calculate the padding needed from this set of delimiters,
* used when calculating if the next frame will fit in
* the aggregate.
*/
bpad = PADBYTES(al_delta) + (bf->bf_state.bfs_ndelim << 2);
/*
* Chain the buffers together
*/
if (bf_prev)
bf_prev->bf_next = bf;
bf_prev = bf;
/*
* If we're leaking frames, just return at this point;
* we've queued a single frame and we don't want to add
* any more.
*/
if (tid->an->an_leak_count) {
status = ATH_AGGR_LEAK_CLOSED;
break;
}
#if 0
/*
* terminate aggregation on a small packet boundary
*/
if (bf->bf_state.bfs_pktlen < ATH_AGGR_MINPLEN) {
status = ATH_AGGR_SHORTPKT;
break;
}
#endif
}
finish:
/*
* Just in case the list was empty when we tried to
* dequeue a packet ..
*/
if (bf_first) {
DPRINTF(sc, ATH_DEBUG_SW_TX_AGGR,
"%s: al=%d bytes; requested %d bytes\n",
__func__, al, bf_first->bf_state.bfs_rc_maxpktlen);
bf_first->bf_state.bfs_al = al;
bf_first->bf_state.bfs_nframes = nframes;
}
return status;
}
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