On Wed, 2008-12-10 at 05:17 -0700, Helmut Schaa wrote:
> This patch fixes sporadic firmware restarts when scanning while associated.
>
> The firmware will quietly cancel a scan (while associated) if the dwell time
> for a channel to be scanned is larger than the time it may stay away from the
> operating channel (because of DTIM catching). Unfortunately the driver is not
> notified about the canceled scan and therefore the scan watchdog timeout will
> be hit and the driver causes a firmware restart which results in
> disassociation. This mainly happens on passive channels which use a dwell time
> of 120 whereas a typical beacon interval is around 100.
>
> The patch changes the dwell time for passive channels to be slightly smaller
> than the actual beacon interval to work around the firmware issue. Furthermore
> the number of allowed beacon misses is increased from one to three as otherwise
> most scans (while associated) won't complete successfully.
>
> However scanning while associated will still fail in corner cases such as a
> beacon intervals below 30.
>
> Signed-off-by: Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx>
Acked-by: Zhu Yi <yi.zhu@xxxxxxxxx>
Thanks,
-yi
> ---
>
> diff --git a/drivers/net/wireless/ipw2x00/ipw2200.c b/drivers/net/wireless/ipw2x00/ipw2200.c
> index dc6eb49..8e7affa 100644
> --- a/drivers/net/wireless/ipw2x00/ipw2200.c
> +++ b/drivers/net/wireless/ipw2x00/ipw2200.c
> @@ -4347,7 +4347,8 @@ static void ipw_handle_missed_beacon(struct ipw_priv *priv,
> return;
> }
>
> - if (priv->status & STATUS_SCANNING) {
> + if (priv->status & STATUS_SCANNING &&
> + missed_count > IPW_MB_SCAN_CANCEL_THRESHOLD) {
> /* Stop scan to keep fw from getting
> * stuck (only if we aren't roaming --
> * otherwise we'll never scan more than 2 or 3
> @@ -6282,6 +6283,20 @@ static void ipw_add_scan_channels(struct ipw_priv *priv,
> }
> }
>
> +static int ipw_passive_dwell_time(struct ipw_priv *priv)
> +{
> + /* staying on passive channels longer than the DTIM interval during a
> + * scan, while associated, causes the firmware to cancel the scan
> + * without notification. Hence, don't stay on passive channels longer
> + * than the beacon interval.
> + */
> + if (priv->status & STATUS_ASSOCIATED
> + && priv->assoc_network->beacon_interval > 10)
> + return priv->assoc_network->beacon_interval - 10;
> + else
> + return 120;
> +}
> +
> static int ipw_request_scan_helper(struct ipw_priv *priv, int type, int direct)
> {
> struct ipw_scan_request_ext scan;
> @@ -6328,7 +6343,7 @@ static int ipw_request_scan_helper(struct ipw_priv *priv, int type, int direct)
> IPW_DEBUG_WX("use passive scanning\n");
> scan_type = IPW_SCAN_PASSIVE_FULL_DWELL_SCAN;
> scan.dwell_time[IPW_SCAN_PASSIVE_FULL_DWELL_SCAN] =
> - cpu_to_le16(120);
> + cpu_to_le16(ipw_passive_dwell_time(priv));
> ipw_add_scan_channels(priv, &scan, scan_type);
> goto send_request;
> }
> @@ -6344,7 +6359,8 @@ static int ipw_request_scan_helper(struct ipw_priv *priv, int type, int direct)
> scan.dwell_time[IPW_SCAN_ACTIVE_BROADCAST_AND_DIRECT_SCAN] =
> cpu_to_le16(20);
>
> - scan.dwell_time[IPW_SCAN_PASSIVE_FULL_DWELL_SCAN] = cpu_to_le16(120);
> + scan.dwell_time[IPW_SCAN_PASSIVE_FULL_DWELL_SCAN] =
> + cpu_to_le16(ipw_passive_dwell_time(priv));
> scan.dwell_time[IPW_SCAN_ACTIVE_DIRECT_SCAN] = cpu_to_le16(20);
>
> #ifdef CONFIG_IPW2200_MONITOR
> diff --git a/drivers/net/wireless/ipw2x00/ipw2200.h b/drivers/net/wireless/ipw2x00/ipw2200.h
> index 0a84d52..277b274 100644
> --- a/drivers/net/wireless/ipw2x00/ipw2200.h
> +++ b/drivers/net/wireless/ipw2x00/ipw2200.h
> @@ -245,6 +245,7 @@ enum connection_manager_assoc_states {
> #define HOST_NOTIFICATION_S36_MEASUREMENT_REFUSED 31
>
> #define HOST_NOTIFICATION_STATUS_BEACON_MISSING 1
> +#define IPW_MB_SCAN_CANCEL_THRESHOLD 3
> #define IPW_MB_ROAMING_THRESHOLD_MIN 1
> #define IPW_MB_ROAMING_THRESHOLD_DEFAULT 8
> #define IPW_MB_ROAMING_THRESHOLD_MAX 30
--
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