3a53731df7
The old value was 30ms, which means mesh sync will treat any value below as merely TSF drift. This isn't really reasonable (typical drift is < 10us/s) since people probably want to adjust TSF in smaller increments (for ie. beacon collision avoidance) without mesh sync fighting back. Change max drift adjustment to 0.8ms, so manual TSF adjustments can be made in 1ms increments, with some margin. Signed-off-by: Thomas Pedersen <twp@qca.qualcomm.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
230 lines
6.8 KiB
C
230 lines
6.8 KiB
C
/*
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* Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
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* Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
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* Copyright 2011-2012, cozybit Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include "ieee80211_i.h"
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#include "mesh.h"
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#include "driver-ops.h"
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/* This is not in the standard. It represents a tolerable tbtt drift below
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* which we do no TSF adjustment.
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*/
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#define TOFFSET_MINIMUM_ADJUSTMENT 10
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/* This is not in the standard. It is a margin added to the
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* Toffset setpoint to mitigate TSF overcorrection
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* introduced by TSF adjustment latency.
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*/
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#define TOFFSET_SET_MARGIN 20
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/* This is not in the standard. It represents the maximum Toffset jump above
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* which we'll invalidate the Toffset setpoint and choose a new setpoint. This
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* could be, for instance, in case a neighbor is restarted and its TSF counter
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* reset.
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*/
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#define TOFFSET_MAXIMUM_ADJUSTMENT 800 /* 0.8 ms */
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struct sync_method {
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u8 method;
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struct ieee80211_mesh_sync_ops ops;
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};
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/**
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* mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
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*
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* @ie: information elements of a management frame from the mesh peer
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*/
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static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
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{
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return (ie->mesh_config->meshconf_cap &
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IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
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}
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void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
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{
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struct ieee80211_local *local = sdata->local;
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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/* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
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u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
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u64 tsf;
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u64 tsfdelta;
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
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msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n",
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(long long) ifmsh->sync_offset_clockdrift_max);
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tsfdelta = -ifmsh->sync_offset_clockdrift_max;
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ifmsh->sync_offset_clockdrift_max = 0;
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} else {
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msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting by %llu\n",
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(long long) ifmsh->sync_offset_clockdrift_max,
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(unsigned long long) beacon_int_fraction);
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tsfdelta = -beacon_int_fraction;
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ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
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}
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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if (local->ops->offset_tsf) {
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drv_offset_tsf(local, sdata, tsfdelta);
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} else {
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tsf = drv_get_tsf(local, sdata);
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if (tsf != -1ULL)
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drv_set_tsf(local, sdata, tsf + tsfdelta);
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}
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}
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static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
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u16 stype,
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struct ieee80211_mgmt *mgmt,
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struct ieee802_11_elems *elems,
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struct ieee80211_rx_status *rx_status)
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{
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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struct ieee80211_local *local = sdata->local;
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struct sta_info *sta;
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u64 t_t, t_r;
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WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
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/* standard mentions only beacons */
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if (stype != IEEE80211_STYPE_BEACON)
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return;
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/*
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* Get time when timestamp field was received. If we don't
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* have rx timestamps, then use current tsf as an approximation.
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* drv_get_tsf() must be called before entering the rcu-read
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* section.
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*/
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if (ieee80211_have_rx_timestamp(rx_status))
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t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
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24 + 12 +
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elems->total_len +
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FCS_LEN,
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24);
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else
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t_r = drv_get_tsf(local, sdata);
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rcu_read_lock();
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sta = sta_info_get(sdata, mgmt->sa);
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if (!sta)
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goto no_sync;
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/* check offset sync conditions (13.13.2.2.1)
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*
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* TODO also sync to
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* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
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*/
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if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
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clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
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sta->sta.addr);
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goto no_sync;
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}
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/* Timing offset calculation (see 13.13.2.2.2) */
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t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
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sta->mesh->t_offset = t_t - t_r;
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if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
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s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset;
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msync_dbg(sdata,
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"STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n",
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sta->sta.addr, (long long) sta->mesh->t_offset,
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(long long) sta->mesh->t_offset_setpoint,
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(long long) t_clockdrift);
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if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
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t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
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msync_dbg(sdata,
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"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
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sta->sta.addr,
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(long long) t_clockdrift);
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clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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goto no_sync;
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}
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
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ifmsh->sync_offset_clockdrift_max = t_clockdrift;
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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} else {
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sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN;
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set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
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msync_dbg(sdata,
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"STA %pM : offset was invalid, t_offset=%lld\n",
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sta->sta.addr,
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(long long) sta->mesh->t_offset);
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}
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no_sync:
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rcu_read_unlock();
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}
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static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata,
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struct beacon_data *beacon)
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{
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struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
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u8 cap;
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WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
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WARN_ON(!rcu_read_lock_held());
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cap = beacon->meshconf->meshconf_cap;
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spin_lock_bh(&ifmsh->sync_offset_lock);
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if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
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/* Since ajusting the tsf here would
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* require a possibly blocking call
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* to the driver tsf setter, we punt
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* the tsf adjustment to the mesh tasklet
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*/
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msync_dbg(sdata,
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"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
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ifmsh->sync_offset_clockdrift_max);
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set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
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ifmsh->adjusting_tbtt = true;
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} else {
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msync_dbg(sdata,
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"TBTT : max clockdrift=%lld; too small to adjust\n",
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(long long)ifmsh->sync_offset_clockdrift_max);
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ifmsh->sync_offset_clockdrift_max = 0;
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ifmsh->adjusting_tbtt = false;
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}
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spin_unlock_bh(&ifmsh->sync_offset_lock);
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beacon->meshconf->meshconf_cap = ifmsh->adjusting_tbtt ?
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IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING | cap :
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~IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING & cap;
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}
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static const struct sync_method sync_methods[] = {
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{
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.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
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.ops = {
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.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
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.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
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}
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},
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};
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const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
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{
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int i;
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for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
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if (sync_methods[i].method == method)
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return &sync_methods[i].ops;
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}
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return NULL;
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}
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