Roaming with Tiwi-r2

Hello,

i am using TiWi01-R2 01-019959 on a Linux 3.2.0 Host with the following drivers:

ti-compat-wireless-wl12xx-0.20121118r5sp3 with Firmware wl127x-fw-4-sr.bin

ti-compat-bluetooth-0.20121119r5sp3 with Firmware TIInit_7.2.31.bts

bt-enable-1.0

These Drivers are included in TI's AM335xSDK 5.06.

Everything runs fine.

From my understanding there should be some roaming Features inside the Firmware wl127x-fw-4-sr.bin, i checked the wl12xx driver and the only thing to influence is in

struct conf_roam_trigger_settings {
    /*
     * The minimum interval between two trigger events.
     *
     * Range: 0 - 60000 ms
     */
    u16 trigger_pacing;

    /*
     * The weight for rssi/beacon average calculation
     *
     * Range: 0 - 255
     */
    u8 avg_weight_rssi_beacon;

    /*
     * The weight for rssi/data frame average calculation
     *
     * Range: 0 - 255
     */
    u8 avg_weight_rssi_data;

    /*
     * The weight for snr/beacon average calculation
     *
     * Range: 0 - 255
     */
    u8 avg_weight_snr_beacon;

    /*
     * The weight for snr/data frame average calculation
     *
     * Range: 0 - 255
     */
    u8 avg_weight_snr_data;
};

 so there must be some values for minimum rssi and so on defined inside the firmware.

Questions:

1. Are there any roaming features inside the Firmware?
2. I would like to let the firmware do all the roaming related tasks such as scanning, iapp and calling cfg80211_roamed. Because i think it is the best way to do it. Ist this possible ?
3. How can i tell the firmware when to consider a connection to an access point to be lost (Bit Rate, Signal level)?
4. Would you recommend to do the roaming in userspace with wpa_supplicant ?

i did some testing in freeradius wpa2 client-certificate enviroment, my observations where as follows:

When i move the AP out of range, the wl1271 stays with it even if the reception is at -99dBm and there is another AP available at -40dBm.

 Bit Rate=1 Mb/s   Tx-Power=20 dBm
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on
          Link Quality=18/70  Signal level=-92 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:253  Invalid misc:1   Missed beacon:0

It seems to me that the station is still recieving beacon frames from the access point. Because of that the firmware considers the connection to be good.

When i stop sending beacon frames to the station the wl1271 handles this as follows:

for 10 seconds it says beacon loss detectet.

After that time the Firmware calls connection loss.

Then it needs to scan on all channels for AP's three times.

Then it associates with the best AP.

•  In the driver i could reduce the beacon loss waiting time, but i feel that this might not be the best way to do it.

If there are no firmware based roaming capabilities that can be exploited, i will start monitoring the link quality in userspace and call the driver for reassociate. I do not consider this to be roaming.

Regards,

Jürgen