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rt2x00: use generic EWMA functions for average RSSI calculations

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

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Gabor Juhos 2013-10-09 11:00:38 +02:00 committed by John W. Linville
parent 8f78b0bb87
commit 1dc254ac9f
3 changed files with 29 additions and 58 deletions
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1
drivers/net/wireless/rt2x00/Kconfig
View File

@ -219,6 +219,7 @@ config RT2X00_LIB_USB
config RT2X00_LIB
tristate
select AVERAGE
config RT2X00_LIB_FIRMWARE
boolean

16
drivers/net/wireless/rt2x00/rt2x00.h
View File

@ -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.

70
drivers/net/wireless/rt2x00/rt2x00link.c
View File

@ -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