[PATCH] zd1211rw: Fix of signal strength and quality measurement

Caused by a documentation issue I mixed up fields of the zd_status
structure. This patch fixes it and improves also the average
computation, which is now using only measurements of packets sent
by the access point.

Signed-off-by: Ulrich Kunitz <kune@deine-taler.de>
Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 88 insertions, 27 deletions

diff --git a/drivers/net/wireless/zd1211rw/zd_chip.c b/drivers/net/wireless/zd1211rw/zd_chip.c
index da9d06bdb818..aa792821854e 100644
--- a/drivers/net/wireless/zd1211rw/zd_chip.c
+++ b/drivers/net/wireless/zd1211rw/zd_chip.c
@@ -1430,9 +1430,43 @@ static int ofdm_qual_db(u8 status_quality, u8 rate, unsigned int size)
                         break;
         }
 
+        switch (rate) {
+        case ZD_OFDM_RATE_6M:
+        case ZD_OFDM_RATE_9M:
+                i += 3;
+                break;
+        case ZD_OFDM_RATE_12M:
+        case ZD_OFDM_RATE_18M:
+                i += 5;
+                break;
+        case ZD_OFDM_RATE_24M:
+        case ZD_OFDM_RATE_36M:
+                i += 9;
+                break;
+        case ZD_OFDM_RATE_48M:
+        case ZD_OFDM_RATE_54M:
+                i += 15;
+                break;
+        default:
+                return -EINVAL;
+        }
+
         return i;
 }
 
+static int ofdm_qual_percent(u8 status_quality, u8 rate, unsigned int size)
+{
+        int r;
+
+        r = ofdm_qual_db(status_quality, rate, size);
+        ZD_ASSERT(r >= 0);
+        if (r < 0)
+                r = 0;
+
+        r = (r * 100)/29;
+        return r <= 100 ? r : 100;
+}
+
 static unsigned int log10times100(unsigned int x)
 {
         static const u8 log10[] = {
@@ -1476,31 +1510,28 @@ static int cck_snr_db(u8 status_quality)
         return r;
 }
 
-static int rx_qual_db(const void *rx_frame, unsigned int size,
-                      const struct rx_status *status)
+static int cck_qual_percent(u8 status_quality)
 {
-        return (status->frame_status&ZD_RX_OFDM) ?
-                ofdm_qual_db(status->signal_quality_ofdm,
-                             zd_ofdm_plcp_header_rate(rx_frame),
-                             size) :
-                cck_snr_db(status->signal_quality_cck);
+        int r;
+
+        r = cck_snr_db(status_quality);
+        r = (100*r)/17;
+        return r <= 100 ? r : 100;
 }
 
 u8 zd_rx_qual_percent(const void *rx_frame, unsigned int size,
                       const struct rx_status *status)
 {
-        int r = rx_qual_db(rx_frame, size, status);
-        if (r < 0)
-                r = 0;
-        r = (r * 100) / 14;
-        if (r > 100)
-                r = 100;
-        return r;
+        return (status->frame_status&ZD_RX_OFDM) ?
+                ofdm_qual_percent(status->signal_quality_ofdm,
+                                  zd_ofdm_plcp_header_rate(rx_frame),
+                                  size) :
+                cck_qual_percent(status->signal_quality_cck);
 }
 
 u8 zd_rx_strength_percent(u8 rssi)
 {
-        int r = (rssi*100) / 30;
+        int r = (rssi*100) / 41;
         if (r > 100)
                 r = 100;
         return (u8) r;
diff --git a/drivers/net/wireless/zd1211rw/zd_mac.c b/drivers/net/wireless/zd1211rw/zd_mac.c
index d6f3e02a0b54..a9bd80a08613 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zd1211rw/zd_mac.c
@@ -816,13 +816,25 @@ static int filter_rx(struct ieee80211_device *ieee,
         return -EINVAL;
 }
 
-static void update_qual_rssi(struct zd_mac *mac, u8 qual_percent, u8 rssi)
+static void update_qual_rssi(struct zd_mac *mac,
+                             const u8 *buffer, unsigned int length,
+                             u8 qual_percent, u8 rssi_percent)
 {
         unsigned long flags;
+        struct ieee80211_hdr_3addr *hdr;
+        int i;
+
+        hdr = (struct ieee80211_hdr_3addr *)buffer;
+        if (length < offsetof(struct ieee80211_hdr_3addr, addr3))
+                return;
+        if (memcmp(hdr->addr2, zd_mac_to_ieee80211(mac)->bssid, ETH_ALEN) != 0)
+                return;
 
         spin_lock_irqsave(&mac->lock, flags);
-        mac->qual_average = (7 * mac->qual_average + qual_percent) / 8;
-        mac->rssi_average = (7 * mac->rssi_average + rssi) / 8;
+        i = mac->stats_count % ZD_MAC_STATS_BUFFER_SIZE;
+        mac->qual_buffer[i] = qual_percent;
+        mac->rssi_buffer[i] = rssi_percent;
+        mac->stats_count++;
         spin_unlock_irqrestore(&mac->lock, flags);
 }
 
@@ -853,7 +865,6 @@ static int fill_rx_stats(struct ieee80211_rx_stats *stats,
         if (stats->rate)
                 stats->mask |= IEEE80211_STATMASK_RATE;
 
-        update_qual_rssi(mac, stats->signal, stats->rssi);
         return 0;
 }
 
@@ -877,6 +888,8 @@ int zd_mac_rx(struct zd_mac *mac, const u8 *buffer, unsigned int length)
                   sizeof(struct rx_status);
         buffer += ZD_PLCP_HEADER_SIZE;
 
+        update_qual_rssi(mac, buffer, length, stats.signal, stats.rssi);
+
         r = filter_rx(ieee, buffer, length, &stats);
         if (r <= 0)
                 return r;
@@ -981,17 +994,31 @@ struct iw_statistics *zd_mac_get_wireless_stats(struct net_device *ndev)
 {
         struct zd_mac *mac = zd_netdev_mac(ndev);
         struct iw_statistics *iw_stats = &mac->iw_stats;
+        unsigned int i, count, qual_total, rssi_total;
 
         memset(iw_stats, 0, sizeof(struct iw_statistics));
         /* We are not setting the status, because ieee->state is not updated
          * at all and this driver doesn't track authentication state.
          */
         spin_lock_irq(&mac->lock);
-        iw_stats->qual.qual = mac->qual_average;
-        iw_stats->qual.level = mac->rssi_average;
-        iw_stats->qual.updated = IW_QUAL_QUAL_UPDATED|IW_QUAL_LEVEL_UPDATED|
-                                 IW_QUAL_NOISE_INVALID;
+        count = mac->stats_count < ZD_MAC_STATS_BUFFER_SIZE ?
+                mac->stats_count : ZD_MAC_STATS_BUFFER_SIZE;
+        qual_total = rssi_total = 0;
+        for (i = 0; i < count; i++) {
+                qual_total += mac->qual_buffer[i];
+                rssi_total += mac->rssi_buffer[i];
+        }
         spin_unlock_irq(&mac->lock);
+        iw_stats->qual.updated = IW_QUAL_NOISE_INVALID;
+        if (count > 0) {
+                iw_stats->qual.qual = qual_total / count;
+                iw_stats->qual.level = rssi_total / count;
+                iw_stats->qual.updated |=
+                        IW_QUAL_QUAL_UPDATED|IW_QUAL_LEVEL_UPDATED;
+        } else {
+                iw_stats->qual.updated |=
+                        IW_QUAL_QUAL_INVALID|IW_QUAL_LEVEL_INVALID;
+        }
         /* TODO: update counter */
         return iw_stats;
 }
diff --git a/drivers/net/wireless/zd1211rw/zd_mac.h b/drivers/net/wireless/zd1211rw/zd_mac.h
index 71e382c589ee..b3ba49b84634 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.h
+++ b/drivers/net/wireless/zd1211rw/zd_mac.h
@@ -1,4 +1,4 @@
-/* zd_mac.c
+/* zd_mac.h
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -87,9 +87,9 @@ struct rx_length_info {
 #define RX_LENGTH_INFO_TAG              0x697e
 
 struct rx_status {
+        u8 signal_quality_cck;
         /* rssi */
         u8 signal_strength;
-        u8 signal_quality_cck;
         u8 signal_quality_ofdm;
         u8 decryption_type;
         u8 frame_status;
@@ -120,14 +120,17 @@ enum mac_flags {
         MAC_FIXED_CHANNEL = 0x01,
 };
 
+#define ZD_MAC_STATS_BUFFER_SIZE 16
+
 struct zd_mac {
         struct net_device *netdev;
         struct zd_chip chip;
         spinlock_t lock;
         /* Unlocked reading possible */
         struct iw_statistics iw_stats;
-        u8 qual_average;
-        u8 rssi_average;
+        unsigned int stats_count;
+        u8 qual_buffer[ZD_MAC_STATS_BUFFER_SIZE];
+        u8 rssi_buffer[ZD_MAC_STATS_BUFFER_SIZE];
         u8 regdomain;
         u8 default_regdomain;
         u8 requested_channel;