/* * Copyright (C) 2010 Bruno Randolf <br1@einfach.org> * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/** * DOC: Basic ANI Operation * * Adaptive Noise Immunity (ANI) controls five noise immunity parameters * depending on the amount of interference in the environment, increasing * or reducing sensitivity as necessary. * * The parameters are: * * - "noise immunity" * * - "spur immunity" * * - "firstep level" * * - "OFDM weak signal detection" * * - "CCK weak signal detection" * * Basically we look at the amount of ODFM and CCK timing errors we get and then * raise or lower immunity accordingly by setting one or more of these * parameters. * * Newer chipsets have PHY error counters in hardware which will generate a MIB * interrupt when they overflow. Older hardware has too enable PHY error frames * by setting a RX flag and then count every single PHY error. When a specified * threshold of errors has been reached we will raise immunity. * Also we regularly check the amount of errors and lower or raise immunity as * necessary.
*/
/***********************\ * ANI parameter control *
\***********************/
/** * ath5k_ani_set_noise_immunity_level() - Set noise immunity level * @ah: The &struct ath5k_hw * @level: level between 0 and @ATH5K_ANI_MAX_NOISE_IMM_LVL
*/ void
ath5k_ani_set_noise_immunity_level(struct ath5k_hw *ah, int level)
{ /* TODO: * ANI documents suggest the following five levels to use, but the HAL * and ath9k use only the last two levels, making this * essentially an on/off option. There *may* be a reason for this (???), * so i stick with the HAL version for now...
*/ #if 0 staticconst s8 lo[] = { -52, -56, -60, -64, -70 }; staticconst s8 hi[] = { -18, -18, -16, -14, -12 }; staticconst s8 sz[] = { -34, -41, -48, -55, -62 }; staticconst s8 fr[] = { -70, -72, -75, -78, -80 }; #else staticconst s8 lo[] = { -64, -70 }; staticconst s8 hi[] = { -14, -12 }; staticconst s8 sz[] = { -55, -62 }; staticconst s8 fr[] = { -78, -80 }; #endif if (level < 0 || level >= ARRAY_SIZE(sz)) {
ATH5K_ERR(ah, "noise immunity level %d out of range",
level); return;
}
/** * ath5k_ani_set_cck_weak_signal_detection() - Set CCK weak signal detection * @ah: The &struct ath5k_hw * @on: turn on or off
*/ void
ath5k_ani_set_cck_weak_signal_detection(struct ath5k_hw *ah, bool on)
{ staticconstint val[] = { 8, 6 };
AR5K_REG_WRITE_BITS(ah, AR5K_PHY_CCK_CROSSCORR,
AR5K_PHY_CCK_CROSSCORR_WEAK_SIG_THR, val[on]);
ah->ani_state.cck_weak_sig = on;
ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_ANI, "turned %s",
on ? "on" : "off");
}
/***************\ * ANI algorithm *
\***************/
/** * ath5k_ani_raise_immunity() - Increase noise immunity * @ah: The &struct ath5k_hw * @as: The &struct ath5k_ani_state * @ofdm_trigger: If this is true we are called because of too many OFDM errors, * the algorithm will tune more parameters then. * * Try to raise noise immunity (=decrease sensitivity) in several steps * depending on the average RSSI of the beacons we received.
*/ staticvoid
ath5k_ani_raise_immunity(struct ath5k_hw *ah, struct ath5k_ani_state *as, bool ofdm_trigger)
{ int rssi = ewma_beacon_rssi_read(&ah->ah_beacon_rssi_avg);
/* AP mode */ if (ah->opmode == NL80211_IFTYPE_AP) { if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL)
ath5k_ani_set_firstep_level(ah, as->firstep_level + 1); return;
}
/* STA and IBSS mode */
/* TODO: for IBSS mode it would be better to keep a beacon RSSI average * per each neighbour node and use the minimum of these, to make sure we
* don't shut out a remote node by raising immunity too high. */
if (rssi > ATH5K_ANI_RSSI_THR_HIGH) {
ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_ANI, "beacon RSSI high"); /* only OFDM: beacon RSSI is high, we can disable ODFM weak
* signal detection */ if (ofdm_trigger && as->ofdm_weak_sig) {
ath5k_ani_set_ofdm_weak_signal_detection(ah, false);
ath5k_ani_set_spur_immunity_level(ah, 0); return;
} /* as a last resort or CCK: raise firstep level */ if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL) {
ath5k_ani_set_firstep_level(ah, as->firstep_level + 1); return;
}
} elseif (rssi > ATH5K_ANI_RSSI_THR_LOW) { /* beacon RSSI in mid range, we need OFDM weak signal detect,
* but can raise firstep level */
ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_ANI, "beacon RSSI mid"); if (ofdm_trigger && !as->ofdm_weak_sig)
ath5k_ani_set_ofdm_weak_signal_detection(ah, true); if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL)
ath5k_ani_set_firstep_level(ah, as->firstep_level + 1); return;
} elseif (ah->ah_current_channel->band == NL80211_BAND_2GHZ) { /* beacon RSSI is low. in B/G mode turn of OFDM weak signal
* detect and zero firstep level to maximize CCK sensitivity */
ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_ANI, "beacon RSSI low, 2GHz"); if (ofdm_trigger && as->ofdm_weak_sig)
ath5k_ani_set_ofdm_weak_signal_detection(ah, false); if (as->firstep_level > 0)
ath5k_ani_set_firstep_level(ah, 0); return;
}
/** * ath5k_ani_lower_immunity() - Decrease noise immunity * @ah: The &struct ath5k_hw * @as: The &struct ath5k_ani_state * * Try to lower noise immunity (=increase sensitivity) in several steps * depending on the average RSSI of the beacons we received.
*/ staticvoid
ath5k_ani_lower_immunity(struct ath5k_hw *ah, struct ath5k_ani_state *as)
{ int rssi = ewma_beacon_rssi_read(&ah->ah_beacon_rssi_avg);
if (ah->opmode == NL80211_IFTYPE_AP) { /* AP mode */ if (as->firstep_level > 0) {
ath5k_ani_set_firstep_level(ah, as->firstep_level - 1); return;
}
} else { /* STA and IBSS mode (see TODO above) */ if (rssi > ATH5K_ANI_RSSI_THR_HIGH) { /* beacon signal is high, leave OFDM weak signal * detection off or it may oscillate
* TODO: who said it's off??? */
} elseif (rssi > ATH5K_ANI_RSSI_THR_LOW) { /* beacon RSSI is mid-range: turn on ODFM weak signal
* detection and next, lower firstep level */ if (!as->ofdm_weak_sig) {
ath5k_ani_set_ofdm_weak_signal_detection(ah, true); return;
} if (as->firstep_level > 0) {
ath5k_ani_set_firstep_level(ah,
as->firstep_level - 1); return;
}
} else { /* beacon signal is low: only reduce firstep level */ if (as->firstep_level > 0) {
ath5k_ani_set_firstep_level(ah,
as->firstep_level - 1); return;
}
}
}
/* all modes */ if (as->spur_level > 0) {
ath5k_ani_set_spur_immunity_level(ah, as->spur_level - 1); return;
}
/** * ath5k_hw_ani_get_listen_time() - Update counters and return listening time * @ah: The &struct ath5k_hw * @as: The &struct ath5k_ani_state * * Return an approximation of the time spent "listening" in milliseconds (ms) * since the last call of this function. * Save a snapshot of the counter values for debugging/statistics.
*/ staticint
ath5k_hw_ani_get_listen_time(struct ath5k_hw *ah, struct ath5k_ani_state *as)
{ struct ath_common *common = ath5k_hw_common(ah); int listen;
/** * ath5k_ani_save_and_clear_phy_errors() - Clear and save PHY error counters * @ah: The &struct ath5k_hw * @as: The &struct ath5k_ani_state * * Clear the PHY error counters as soon as possible, since this might be called * from a MIB interrupt and we want to make sure we don't get interrupted again. * Add the count of CCK and OFDM errors to our internal state, so it can be used * by the algorithm later. * * Will be called from interrupt and tasklet context. * Returns 0 if both counters are zero.
*/ staticint
ath5k_ani_save_and_clear_phy_errors(struct ath5k_hw *ah, struct ath5k_ani_state *as)
{ unsignedint ofdm_err, cck_err;
if (!ah->ah_capabilities.cap_has_phyerr_counters) return 0;
/* sometimes both can be zero, especially when there is a superfluous
* second interrupt. detect that here and return an error. */ if (ofdm_err <= 0 && cck_err <= 0) return 0;
/* avoid negative values should one of the registers overflow */ if (ofdm_err > 0) {
as->ofdm_errors += ofdm_err;
as->sum_ofdm_errors += ofdm_err;
} if (cck_err > 0) {
as->cck_errors += cck_err;
as->sum_cck_errors += cck_err;
} return 1;
}
/** * ath5k_ani_period_restart() - Restart ANI period * @as: The &struct ath5k_ani_state * * Just reset counters, so they are clear for the next "ani period".
*/ staticvoid
ath5k_ani_period_restart(struct ath5k_ani_state *as)
{ /* keep last values for debugging */
as->last_ofdm_errors = as->ofdm_errors;
as->last_cck_errors = as->cck_errors;
as->last_listen = as->listen_time;
/** * ath5k_ani_calibration() - The main ANI calibration function * @ah: The &struct ath5k_hw * * We count OFDM and CCK errors relative to the time where we did not send or * receive ("listen" time) and raise or lower immunity accordingly. * This is called regularly (every second) from the calibration timer, but also * when an error threshold has been reached. * * In order to synchronize access from different contexts, this should be * called only indirectly by scheduling the ANI tasklet!
*/ void
ath5k_ani_calibration(struct ath5k_hw *ah)
{ struct ath5k_ani_state *as = &ah->ani_state; int listen, ofdm_high, ofdm_low, cck_high, cck_low;
/* get listen time since last call and add it to the counter because we * might not have restarted the "ani period" last time.
* always do this to calculate the busy time also in manual mode */
listen = ath5k_hw_ani_get_listen_time(ah, as);
as->listen_time += listen;
if (as->ofdm_errors > ofdm_high || as->cck_errors > cck_high) { /* too many PHY errors - we have to raise immunity */ bool ofdm_flag = as->ofdm_errors > ofdm_high;
ath5k_ani_raise_immunity(ah, as, ofdm_flag);
ath5k_ani_period_restart(as);
} elseif (as->listen_time > 5 * ATH5K_ANI_LISTEN_PERIOD) { /* If more than 5 (TODO: why 5?) periods have passed and we got
* relatively little errors we can try to lower immunity */
ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_ANI, "check low ofdm %d/%d cck %d/%d",
as->ofdm_errors, ofdm_low, as->cck_errors, cck_low);
if (as->ofdm_errors <= ofdm_low && as->cck_errors <= cck_low)
ath5k_ani_lower_immunity(ah, as);
/** * ath5k_ani_mib_intr() - Interrupt handler for ANI MIB counters * @ah: The &struct ath5k_hw * * Just read & reset the registers quickly, so they don't generate more * interrupts, save the counters and schedule the tasklet to decide whether * to raise immunity or not. * * We just need to handle PHY error counters, ath5k_hw_update_mib_counters() * should take care of all "normal" MIB interrupts.
*/ void
ath5k_ani_mib_intr(struct ath5k_hw *ah)
{ struct ath5k_ani_state *as = &ah->ani_state;
/* nothing to do here if HW does not have PHY error counters - they
* can't be the reason for the MIB interrupt then */ if (!ah->ah_capabilities.cap_has_phyerr_counters) return;
/* not in use but clear anyways */
ath5k_hw_reg_write(ah, 0, AR5K_OFDM_FIL_CNT);
ath5k_hw_reg_write(ah, 0, AR5K_CCK_FIL_CNT);
if (ah->ani_state.ani_mode != ATH5K_ANI_MODE_AUTO) return;
/* If one of the errors triggered, we can get a superfluous second * interrupt, even though we have already reset the register. The
* function detects that so we can return early. */ if (ath5k_ani_save_and_clear_phy_errors(ah, as) == 0) return;
if (as->ofdm_errors > ATH5K_ANI_OFDM_TRIG_HIGH ||
as->cck_errors > ATH5K_ANI_CCK_TRIG_HIGH)
tasklet_schedule(&ah->ani_tasklet);
}
/** * ath5k_ani_phy_error_report - Used by older HW to report PHY errors * * @ah: The &struct ath5k_hw * @phyerr: One of enum ath5k_phy_error_code * * This is used by hardware without PHY error counters to report PHY errors * on a frame-by-frame basis, instead of the interrupt.
*/ void
ath5k_ani_phy_error_report(struct ath5k_hw *ah, enum ath5k_phy_error_code phyerr)
{ struct ath5k_ani_state *as = &ah->ani_state;
if (phyerr == AR5K_RX_PHY_ERROR_OFDM_TIMING) {
as->ofdm_errors++; if (as->ofdm_errors > ATH5K_ANI_OFDM_TRIG_HIGH)
tasklet_schedule(&ah->ani_tasklet);
} elseif (phyerr == AR5K_RX_PHY_ERROR_CCK_TIMING) {
as->cck_errors++; if (as->cck_errors > ATH5K_ANI_CCK_TRIG_HIGH)
tasklet_schedule(&ah->ani_tasklet);
}
}
/* not in use */
ath5k_hw_reg_write(ah, 0, AR5K_OFDM_FIL_CNT);
ath5k_hw_reg_write(ah, 0, AR5K_CCK_FIL_CNT);
}
/** * ath5k_ani_init() - Initialize ANI * @ah: The &struct ath5k_hw * @mode: One of enum ath5k_ani_mode * * Initialize ANI according to mode.
*/ void
ath5k_ani_init(struct ath5k_hw *ah, enum ath5k_ani_mode mode)
{ /* ANI is only possible on 5212 and newer */ if (ah->ah_version < AR5K_AR5212) return;
if (mode < ATH5K_ANI_MODE_OFF || mode > ATH5K_ANI_MODE_AUTO) {
ATH5K_ERR(ah, "ANI mode %d out of range", mode); return;
}
/* clear old state information */
memset(&ah->ani_state, 0, sizeof(ah->ani_state));
/* older hardware has more spur levels than newer */ if (ah->ah_mac_srev < AR5K_SREV_AR2414)
ah->ani_state.max_spur_level = 7; else
ah->ani_state.max_spur_level = 2;
/* newer hardware has PHY error counter registers which we can use to * get OFDM and CCK error counts. older hardware has to set rxfilter and * report every single PHY error by calling ath5k_ani_phy_error_report()
*/ if (mode == ATH5K_ANI_MODE_AUTO) { if (ah->ah_capabilities.cap_has_phyerr_counters)
ath5k_enable_phy_err_counters(ah); else
ath5k_hw_set_rx_filter(ah, ath5k_hw_get_rx_filter(ah) |
AR5K_RX_FILTER_PHYERR);
} else { if (ah->ah_capabilities.cap_has_phyerr_counters)
ath5k_disable_phy_err_counters(ah); else
ath5k_hw_set_rx_filter(ah, ath5k_hw_get_rx_filter(ah) &
~AR5K_RX_FILTER_PHYERR);
}
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