On Thu, Dec 4, 2008 at 5:21 AM, Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote:
> The current wireless statistics for the RTL8187 poorly indicate the signal
> strength and quality. With testing, I found that the AGC value is inversely
> correlated with the strength as in the RTL8187B. By implementing a similar
> calculation, much more code becomes common to the two devices.
>
> Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
> Tested by: Martín Ernesto Barreyro <barreyromartin@xxxxxxxxx>
> ---
>
> John,
>
> This is 2.6.29 material.
>
> Larry
> ---
>
> Index: wireless-testing/drivers/net/wireless/rtl818x/rtl8187_dev.c
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/rtl818x/rtl8187_dev.c
> +++ wireless-testing/drivers/net/wireless/rtl818x/rtl8187_dev.c
> @@ -313,29 +313,14 @@ static void rtl8187_rx_cb(struct urb *ur
> struct rtl8187_rx_hdr *hdr =
> (typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
> flags = le32_to_cpu(hdr->flags);
> - signal = hdr->signal & 0x7f;
> + /* As with the RTL8187B below, the AGC is used to calculate
> + * signal strength and quality. In this case, the scaling
> + * constants are derived from the output of p54usb.
> + */
> + quality = 130 - ((41 * hdr->agc) >> 6);
> + signal = -4 - ((27 * hdr->agc) >> 6);
> rx_status.antenna = (hdr->signal >> 7) & 1;
> - rx_status.noise = hdr->noise;
> rx_status.mactime = le64_to_cpu(hdr->mac_time);
> - priv->quality = signal;
> - rx_status.qual = priv->quality;
> - priv->noise = hdr->noise;
> - rate = (flags >> 20) & 0xF;
> - if (rate > 3) { /* OFDM rate */
> - if (signal > 90)
> - signal = 90;
> - else if (signal < 25)
> - signal = 25;
> - signal = 90 - signal;
> - } else { /* CCK rate */
> - if (signal > 95)
> - signal = 95;
> - else if (signal < 30)
> - signal = 30;
> - signal = 95 - signal;
> - }
> - rx_status.signal = signal;
> - priv->signal = signal;
> } else {
> struct rtl8187b_rx_hdr *hdr =
> (typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
> @@ -353,18 +338,18 @@ static void rtl8187_rx_cb(struct urb *ur
> */
> flags = le32_to_cpu(hdr->flags);
> quality = 170 - hdr->agc;
> - if (quality > 100)
> - quality = 100;
> signal = 14 - hdr->agc / 2;
> - rx_status.qual = quality;
> - priv->quality = quality;
> - rx_status.signal = signal;
> - priv->signal = signal;
> rx_status.antenna = (hdr->rssi >> 7) & 1;
> rx_status.mactime = le64_to_cpu(hdr->mac_time);
> - rate = (flags >> 20) & 0xF;
> }
>
> + if (quality > 100)
> + quality = 100;
> + rx_status.qual = quality;
> + priv->quality = quality;
> + rx_status.signal = signal;
> + priv->signal = signal;
> + rate = (flags >> 20) & 0xF;
> skb_trim(skb, flags & 0x0FFF);
> rx_status.rate_idx = rate;
> rx_status.freq = dev->conf.channel->center_freq;
> @@ -1294,6 +1279,7 @@ static int __devinit rtl8187_probe(struc
>
> priv->mode = NL80211_IFTYPE_MONITOR;
> dev->flags = IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
> + IEEE80211_HW_SIGNAL_DBM |
> IEEE80211_HW_RX_INCLUDES_FCS;
>
> eeprom.data = dev;
> @@ -1409,13 +1395,8 @@ static int __devinit rtl8187_probe(struc
> (*channel++).hw_value = txpwr >> 8;
> }
>
> - if (priv->is_rtl8187b) {
> + if (priv->is_rtl8187b)
> printk(KERN_WARNING "rtl8187: 8187B chip detected.\n");
> - dev->flags |= IEEE80211_HW_SIGNAL_DBM;
> - } else {
> - dev->flags |= IEEE80211_HW_SIGNAL_UNSPEC;
> - dev->max_signal = 65;
> - }
>
> /*
> * XXX: Once this driver supports anything that requires
> --
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>
BTW using RTL8187B's scaling constants for RTL8187L also work well
with this patch - I get almost identical readings from my BCM4318 and
my RTL8187L. (I haven't yet submitted my version of the patch because
it's pretty messy, with #if 0'd code and such.) I wonder whether b43
or p54usb is more correct... However, it looks like the same algorithm
is applicable for both RTL8187 variants.
--
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