I wasn't really satisfied with a graphical program that displayed the link quality, the display was bit erratically. While changing this, I noticed some other things which this and the next patch addresses. However, for this patch I'm not sure if it goes into the right direction. This changes the quality calculation for wireless statistics to only consider signal & noise, but not number of tx-retries. Also changes a the rather complicated formular for quality to be more like http://www.ces.clemson.edu/linux/signal_quality.shtml. Note that tx_retries are no longer used for the quality number. I don't know of any other driver that does it, and tx_retries is only increasing, so the quality would become smaller and smaller ... which wouldn't reflect reality. Questionable things: I also found that the average noise floor is -86 dBm, not -96 dBm. So I changed this constant. Maybe this is wrong, what values do your cards report? The wireless stats have SNR and noise floor to calcutate the quality. However, the scanning logic (for "iwlist XXX scan") only has a not-really-described dimensionless RSSI value. So the quality display for both outputs are a bit different, althought not too much. I don't know any good method, not even from above website, that would make both calculation results identical. However, this was also not the case with the old code. Index: wireless-testing/drivers/net/wireless/libertas/wext.c =================================================================== --- wireless-testing.orig/drivers/net/wireless/libertas/wext.c 2008-03-18 13:42:42.000000000 +0100 +++ wireless-testing/drivers/net/wireless/libertas/wext.c 2008-03-18 13:42:55.000000000 +0100 @@ -805,21 +805,8 @@ out: static struct iw_statistics *lbs_get_wireless_stats(struct net_device *dev) { - enum { - POOR = 30, - FAIR = 60, - GOOD = 80, - VERY_GOOD = 90, - EXCELLENT = 95, - PERFECT = 100 - }; struct lbs_private *priv = dev->priv; - u32 rssi_qual; - u32 tx_qual; - u32 quality = 0; int stats_valid = 0; - u8 rssi; - u32 tx_retries; struct cmd_ds_802_11_get_log log; u16 snr, nf; @@ -838,24 +825,6 @@ static struct iw_statistics *lbs_get_wir priv->wstats.qual.level = CAL_RSSI(snr, nf); priv->wstats.qual.noise = CAL_NF(nf); - lbs_deb_wext("signal level %#x\n", priv->wstats.qual.level); - lbs_deb_wext("noise %#x\n", priv->wstats.qual.noise); - - rssi = priv->wstats.qual.level - priv->wstats.qual.noise; - if (rssi < 15) - rssi_qual = rssi * POOR / 10; - else if (rssi < 20) - rssi_qual = (rssi - 15) * (FAIR - POOR) / 5 + POOR; - else if (rssi < 30) - rssi_qual = (rssi - 20) * (GOOD - FAIR) / 5 + FAIR; - else if (rssi < 40) - rssi_qual = (rssi - 30) * (VERY_GOOD - GOOD) / - 10 + GOOD; - else - rssi_qual = (rssi - 40) * (PERFECT - VERY_GOOD) / - 10 + VERY_GOOD; - quality = rssi_qual; - /* Quality by TX errors */ priv->wstats.discard.retries = priv->stats.tx_errors; @@ -863,28 +832,19 @@ static struct iw_statistics *lbs_get_wir log.hdr.size = cpu_to_le16(sizeof(log)); lbs_cmd_with_response(priv, CMD_802_11_GET_LOG, &log); - tx_retries = le32_to_cpu(log.retry); - - if (tx_retries > 75) - tx_qual = (90 - tx_retries) * POOR / 15; - else if (tx_retries > 70) - tx_qual = (75 - tx_retries) * (FAIR - POOR) / 5 + POOR; - else if (tx_retries > 65) - tx_qual = (70 - tx_retries) * (GOOD - FAIR) / 5 + FAIR; - else if (tx_retries > 50) - tx_qual = (65 - tx_retries) * (VERY_GOOD - GOOD) / - 15 + GOOD; - else - tx_qual = (50 - tx_retries) * - (PERFECT - VERY_GOOD) / 50 + VERY_GOOD; - quality = min(quality, tx_qual); - priv->wstats.discard.code = le32_to_cpu(log.wepundecryptable); - priv->wstats.discard.retries = tx_retries; + priv->wstats.discard.retries = le32_to_cpu(log.retry); priv->wstats.discard.misc = le32_to_cpu(log.ackfailure); /* Calculate quality */ - priv->wstats.qual.qual = min_t(u8, quality, 100); + /* see http://www.ces.clemson.edu/linux/signal_quality.shtml */ + snr = priv->wstats.qual.level - priv->wstats.qual.noise; + if (snr <= 0) + priv->wstats.qual.qual = 0; + else if (snr >= 40) + priv->wstats.qual.qual = 100; + else + priv->wstats.qual.qual = 5*snr/2; priv->wstats.qual.updated = IW_QUAL_ALL_UPDATED | IW_QUAL_DBM; stats_valid = 1; Index: wireless-testing/drivers/net/wireless/libertas/defs.h =================================================================== --- wireless-testing.orig/drivers/net/wireless/libertas/defs.h 2008-03-18 13:42:42.000000000 +0100 +++ wireless-testing/drivers/net/wireless/libertas/defs.h 2008-03-18 13:42:55.000000000 +0100 @@ -208,12 +208,9 @@ static inline void lbs_deb_hex(unsigned #define RxPD_MESH_FRAME RxPD_CONTROL_WDS_FRAME /** RSSI-related defines */ -/* RSSI constants are used to implement 802.11 RSSI threshold -* indication. if the Rx packet signal got too weak for 5 consecutive -* times, miniport driver (driver) will report this event to wrapper -*/ -#define MRVDRV_NF_DEFAULT_SCAN_VALUE (-96) +/* This is the average noise level */ +#define MRVDRV_NF_DEFAULT_SCAN_VALUE (-86) /** RTS/FRAG related defines */ #define MRVDRV_RTS_MIN_VALUE 0 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
