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Commit 1dc254ac authored by Gabor Juhos's avatar Gabor Juhos Committed by John W. Linville
Browse files

rt2x00: use generic EWMA functions for average RSSI calculations 



Remove the local MOVING_AVERAGE implementation, and use
the generic EWMA functions instead.

Signed-off-by: default avatarGabor Juhos <juhosg@openwrt.org>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 8f78b0bb

drivers/net/wireless/rt2x00/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ config RT2X00_LIB_USB 


config RT2X00_LIB

	tristate

	select AVERAGE



config RT2X00_LIB_FIRMWARE

	boolean

drivers/net/wireless/rt2x00/rt2x00.h

+3 −13
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#include <linux/input-polldev.h>

#include <linux/kfifo.h>

#include <linux/hrtimer.h>

#include <linux/average.h>



#include <net/mac80211.h>
@@ -138,17 +139,6 @@ 
#define SHORT_EIFS		( SIFS + SHORT_DIFS + \

				  GET_DURATION(IEEE80211_HEADER + ACK_SIZE, 10) )



/*

 * Structure for average calculation

 * The avg field contains the actual average value,

 * but avg_weight is internally used during calculations

 * to prevent rounding errors.

 */

struct avg_val {

	int avg;

	int avg_weight;

};



enum rt2x00_chip_intf {

	RT2X00_CHIP_INTF_PCI,

	RT2X00_CHIP_INTF_PCIE,
@@ -297,7 +287,7 @@ struct link_ant { 
	 * Similar to the avg_rssi in the link_qual structure

	 * this value is updated by using the walking average.

	 */

	struct avg_val rssi_ant;

	struct ewma rssi_ant;

};



/*
@@ -326,7 +316,7 @@ struct link { 
	/*

	 * Currently active average RSSI value

	 */

	struct avg_val avg_rssi;

	struct ewma avg_rssi;



	/*

	 * Work structure for scheduling periodic link tuning.

drivers/net/wireless/rt2x00/rt2x00link.c

+25 −45
Original line number Diff line number Diff line
@@ -35,50 +35,28 @@ 
 */

#define DEFAULT_RSSI		-128



/*

 * Helper struct and macro to work with moving/walking averages.

 * When adding a value to the average value the following calculation

 * is needed:

 *

 *        avg_rssi = ((avg_rssi * 7) + rssi) / 8;

 *

 * The advantage of this approach is that we only need 1 variable

 * to store the average in (No need for a count and a total).

 * But more importantly, normal average values will over time

 * move less and less towards newly added values this results

 * that with link tuning, the device can have a very good RSSI

 * for a few minutes but when the device is moved away from the AP

 * the average will not decrease fast enough to compensate.

 * The walking average compensates this and will move towards

 * the new values correctly allowing a effective link tuning,

 * the speed of the average moving towards other values depends

 * on the value for the number of samples. The higher the number

 * of samples, the slower the average will move.

 * We use two variables to keep track of the average value to

 * compensate for the rounding errors. This can be a significant

 * error (>5dBm) if the factor is too low.

 */

#define AVG_SAMPLES	8

#define AVG_FACTOR	1000

#define MOVING_AVERAGE(__avg, __val) \

({ \

	struct avg_val __new; \

	__new.avg_weight = \

	    (__avg).avg_weight  ? \

		((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \

		  ((__val) * (AVG_FACTOR))) / \

		 (AVG_SAMPLES)) : \

		((__val) * (AVG_FACTOR)); \

	__new.avg = __new.avg_weight / (AVG_FACTOR); \

	__new; \

})

/* Constants for EWMA calculations. */

#define RT2X00_EWMA_FACTOR	1024

#define RT2X00_EWMA_WEIGHT	8



static inline int rt2x00link_get_avg_rssi(struct ewma *ewma)

{

	unsigned long avg;



	avg = ewma_read(ewma);

	if (avg)

		return -avg;



	return DEFAULT_RSSI;

}



static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)

{

	struct link_ant *ant = &rt2x00dev->link.ant;



	if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)

		return ant->rssi_ant.avg;

	if (rt2x00dev->link.qual.rx_success)

		return rt2x00link_get_avg_rssi(&ant->rssi_ant);



	return DEFAULT_RSSI;

}
@@ -100,8 +78,8 @@ static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev, 


static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)

{

	rt2x00dev->link.ant.rssi_ant.avg = 0;

	rt2x00dev->link.ant.rssi_ant.avg_weight = 0;

	ewma_init(&rt2x00dev->link.ant.rssi_ant, RT2X00_EWMA_FACTOR,

		  RT2X00_EWMA_WEIGHT);

}



static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
@@ -249,12 +227,12 @@ void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev, 
	/*

	 * Update global RSSI

	 */

	link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);

	ewma_add(&link->avg_rssi, -rxdesc->rssi);



	/*

	 * Update antenna RSSI

	 */

	ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);

	ewma_add(&ant->rssi_ant, -rxdesc->rssi);

}



void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
@@ -309,6 +287,8 @@ void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna) 
	 */

	rt2x00dev->link.count = 0;

	memset(qual, 0, sizeof(*qual));

	ewma_init(&rt2x00dev->link.avg_rssi, RT2X00_EWMA_FACTOR,

		  RT2X00_EWMA_WEIGHT);



	/*

	 * Restore the VGC level as stored in the registers,
@@ -363,10 +343,10 @@ static void rt2x00link_tuner(struct work_struct *work) 
	 * collect the RSSI data we could use this. Otherwise we

	 * must fallback to the default RSSI value.

	 */

	if (!link->avg_rssi.avg || !qual->rx_success)

	if (!qual->rx_success)

		qual->rssi = DEFAULT_RSSI;

	else

		qual->rssi = link->avg_rssi.avg;

		qual->rssi = rt2x00link_get_avg_rssi(&link->avg_rssi);



	/*

	 * Check if link tuning is supported by the hardware, some hardware