forked from Minki/linux
193df183b1
Antanna quality statistics is not handled correctly, which leads to software diversity being shutdown completly. The main problem is that during antenna diversity statistics can be reset resulting in loosing the signal strength just before evaluation. rssi history is not updated correctly leading to incorrect comparison material for basing antenna switching on. Signed-off-by: Lars Ericsson <Lars_Ericsson@telia.com> Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
467 lines
13 KiB
C
467 lines
13 KiB
C
/*
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Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
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<http://rt2x00.serialmonkey.com>
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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 as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the
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Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/*
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Module: rt2x00lib
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Abstract: rt2x00 generic link tuning routines.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include "rt2x00.h"
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#include "rt2x00lib.h"
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/*
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* When we lack RSSI information return something less then -80 to
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* tell the driver to tune the device to maximum sensitivity.
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*/
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#define DEFAULT_RSSI -128
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/*
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* When no TX/RX percentage could be calculated due to lack of
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* frames on the air, we fallback to a percentage of 50%.
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* This will assure we will get at least get some decent value
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* when the link tuner starts.
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* The value will be dropped and overwritten with the correct (measured)
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* value anyway during the first run of the link tuner.
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*/
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#define DEFAULT_PERCENTAGE 50
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/*
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* Small helper macro to work with moving/walking averages.
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* When adding a value to the average value the following calculation
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* is needed:
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*
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* avg_rssi = ((avg_rssi * 7) + rssi) / 8;
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*
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* The advantage of this approach is that we only need 1 variable
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* to store the average in (No need for a count and a total).
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* But more importantly, normal average values will over time
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* move less and less towards newly added values this results
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* that with link tuning, the device can have a very good RSSI
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* for a few minutes but when the device is moved away from the AP
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* the average will not decrease fast enough to compensate.
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* The walking average compensates this and will move towards
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* the new values correctly allowing a effective link tuning.
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*/
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#define MOVING_AVERAGE(__avg, __val, __samples) \
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( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )
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/*
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* Small helper macro for percentage calculation
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* This is a very simple macro with the only catch that it will
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* produce a default value in case no total value was provided.
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*/
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#define PERCENTAGE(__value, __total) \
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( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )
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/*
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* For calculating the Signal quality we have determined
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* the total number of success and failed RX and TX frames.
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* With the addition of the average RSSI value we can determine
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* the link quality using the following algorithm:
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*
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* rssi_percentage = (avg_rssi * 100) / rssi_offset
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* rx_percentage = (rx_success * 100) / rx_total
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* tx_percentage = (tx_success * 100) / tx_total
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* avg_signal = ((WEIGHT_RSSI * avg_rssi) +
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* (WEIGHT_TX * tx_percentage) +
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* (WEIGHT_RX * rx_percentage)) / 100
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*
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* This value should then be checked to not be greater then 100.
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* This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
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* sum up to 100 as well.
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*/
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#define WEIGHT_RSSI 20
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#define WEIGHT_RX 40
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#define WEIGHT_TX 40
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static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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if (ant->rssi_ant && rt2x00dev->link.qual.rx_success)
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return ant->rssi_ant;
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return DEFAULT_RSSI;
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}
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static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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if (ant->rssi_history)
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return ant->rssi_history;
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return DEFAULT_RSSI;
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}
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static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
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int rssi)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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ant->rssi_history = rssi;
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}
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static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
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{
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rt2x00dev->link.ant.rssi_ant = 0;
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}
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static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct antenna_setup new_ant;
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int other_antenna;
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int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
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int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
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memcpy(&new_ant, &ant->active, sizeof(new_ant));
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/*
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* We are done sampling. Now we should evaluate the results.
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*/
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ant->flags &= ~ANTENNA_MODE_SAMPLE;
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/*
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* During the last period we have sampled the RSSI
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* from both antennas. It now is time to determine
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* which antenna demonstrated the best performance.
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* When we are already on the antenna with the best
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* performance, just create a good starting point
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* for the history and we are done.
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*/
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if (sample_current >= sample_other) {
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rt2x00link_antenna_update_rssi_history(rt2x00dev,
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sample_current);
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return;
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}
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other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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if (ant->flags & ANTENNA_RX_DIVERSITY)
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new_ant.rx = other_antenna;
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if (ant->flags & ANTENNA_TX_DIVERSITY)
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new_ant.tx = other_antenna;
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rt2x00lib_config_antenna(rt2x00dev, new_ant);
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}
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static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct antenna_setup new_ant;
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int rssi_curr;
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int rssi_old;
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memcpy(&new_ant, &ant->active, sizeof(new_ant));
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/*
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* Get current RSSI value along with the historical value,
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* after that update the history with the current value.
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*/
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rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
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rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
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rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);
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/*
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* Legacy driver indicates that we should swap antenna's
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* when the difference in RSSI is greater that 5. This
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* also should be done when the RSSI was actually better
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* then the previous sample.
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* When the difference exceeds the threshold we should
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* sample the rssi from the other antenna to make a valid
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* comparison between the 2 antennas.
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*/
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if (abs(rssi_curr - rssi_old) < 5)
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return;
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ant->flags |= ANTENNA_MODE_SAMPLE;
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if (ant->flags & ANTENNA_RX_DIVERSITY)
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new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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if (ant->flags & ANTENNA_TX_DIVERSITY)
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new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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rt2x00lib_config_antenna(rt2x00dev, new_ant);
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}
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static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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unsigned int flags = ant->flags;
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/*
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* Determine if software diversity is enabled for
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* either the TX or RX antenna (or both).
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* Always perform this check since within the link
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* tuner interval the configuration might have changed.
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*/
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flags &= ~ANTENNA_RX_DIVERSITY;
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flags &= ~ANTENNA_TX_DIVERSITY;
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if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
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flags |= ANTENNA_RX_DIVERSITY;
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if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
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flags |= ANTENNA_TX_DIVERSITY;
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if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
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!(ant->flags & ANTENNA_TX_DIVERSITY)) {
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ant->flags = 0;
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return true;
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}
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/* Update flags */
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ant->flags = flags;
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/*
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* If we have only sampled the data over the last period
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* we should now harvest the data. Otherwise just evaluate
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* the data. The latter should only be performed once
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* every 2 seconds.
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*/
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if (ant->flags & ANTENNA_MODE_SAMPLE) {
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rt2x00lib_antenna_diversity_sample(rt2x00dev);
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return true;
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} else if (rt2x00dev->link.count & 1) {
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rt2x00lib_antenna_diversity_eval(rt2x00dev);
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return true;
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}
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return false;
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}
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void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
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struct sk_buff *skb,
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struct rxdone_entry_desc *rxdesc)
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{
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
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int avg_rssi = rxdesc->rssi;
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int ant_rssi = rxdesc->rssi;
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/*
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* Frame was received successfully since non-succesfull
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* frames would have been dropped by the hardware.
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*/
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qual->rx_success++;
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/*
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* We are only interested in quality statistics from
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* beacons which came from the BSS which we are
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* associated with.
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*/
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if (!ieee80211_is_beacon(hdr->frame_control) ||
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!(rxdesc->dev_flags & RXDONE_MY_BSS))
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return;
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/*
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* Update global RSSI
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*/
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if (link->avg_rssi)
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avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
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link->avg_rssi = avg_rssi;
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/*
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* Update antenna RSSI
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*/
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if (ant->rssi_ant)
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ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
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ant->rssi_ant = ant_rssi;
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}
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static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
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{
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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link->rx_percentage =
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PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
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link->tx_percentage =
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PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
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}
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int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
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{
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struct link *link = &rt2x00dev->link;
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int rssi_percentage = 0;
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int signal;
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/*
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* We need a positive value for the RSSI.
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*/
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if (rssi < 0)
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rssi += rt2x00dev->rssi_offset;
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/*
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* Calculate the different percentages,
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* which will be used for the signal.
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*/
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rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);
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/*
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* Add the individual percentages and use the WEIGHT
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* defines to calculate the current link signal.
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*/
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signal = ((WEIGHT_RSSI * rssi_percentage) +
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(WEIGHT_TX * link->tx_percentage) +
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(WEIGHT_RX * link->rx_percentage)) / 100;
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return max_t(int, signal, 100);
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}
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void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
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{
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struct link *link = &rt2x00dev->link;
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/*
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* Link tuning should only be performed when
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* an active sta or master interface exists.
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* Single monitor mode interfaces should never have
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* work with link tuners.
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*/
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if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
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return;
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link->rx_percentage = DEFAULT_PERCENTAGE;
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link->tx_percentage = DEFAULT_PERCENTAGE;
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rt2x00link_reset_tuner(rt2x00dev, false);
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ieee80211_queue_delayed_work(rt2x00dev->hw,
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&link->work, LINK_TUNE_INTERVAL);
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}
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void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
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{
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cancel_delayed_work_sync(&rt2x00dev->link.work);
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}
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void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
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{
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struct link_qual *qual = &rt2x00dev->link.qual;
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if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
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return;
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/*
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* Reset link information.
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* Both the currently active vgc level as well as
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* the link tuner counter should be reset. Resetting
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* the counter is important for devices where the
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* device should only perform link tuning during the
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* first minute after being enabled.
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*/
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rt2x00dev->link.count = 0;
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memset(qual, 0, sizeof(*qual));
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/*
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* Reset the link tuner.
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*/
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rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
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if (antenna)
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rt2x00link_antenna_reset(rt2x00dev);
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}
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static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
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{
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struct link_qual *qual = &rt2x00dev->link.qual;
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qual->rx_success = 0;
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qual->rx_failed = 0;
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qual->tx_success = 0;
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qual->tx_failed = 0;
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}
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static void rt2x00link_tuner(struct work_struct *work)
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{
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struct rt2x00_dev *rt2x00dev =
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container_of(work, struct rt2x00_dev, link.work.work);
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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/*
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* When the radio is shutting down we should
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* immediately cease all link tuning.
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*/
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if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
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return;
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/*
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* Update statistics.
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*/
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rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
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rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
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/*
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* Update quality RSSI for link tuning,
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* when we have received some frames and we managed to
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* collect the RSSI data we could use this. Otherwise we
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* must fallback to the default RSSI value.
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*/
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if (!link->avg_rssi || !qual->rx_success)
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qual->rssi = DEFAULT_RSSI;
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else
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qual->rssi = link->avg_rssi;
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/*
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* Only perform the link tuning when Link tuning
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* has been enabled (This could have been disabled from the EEPROM).
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*/
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if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
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rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
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/*
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* Precalculate a portion of the link signal which is
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* in based on the tx/rx success/failure counters.
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*/
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rt2x00link_precalculate_signal(rt2x00dev);
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/*
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* Send a signal to the led to update the led signal strength.
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*/
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rt2x00leds_led_quality(rt2x00dev, link->avg_rssi);
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/*
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* Evaluate antenna setup, make this the last step when
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* rt2x00lib_antenna_diversity made changes the quality
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* statistics will be reset.
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*/
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if (rt2x00lib_antenna_diversity(rt2x00dev))
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rt2x00link_reset_qual(rt2x00dev);
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/*
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* Increase tuner counter, and reschedule the next link tuner run.
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*/
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link->count++;
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ieee80211_queue_delayed_work(rt2x00dev->hw,
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&link->work, LINK_TUNE_INTERVAL);
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}
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void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
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{
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INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
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}
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