Hi Johannes,
> Yeah, and it would do much more than what you want. You could use
> cfg80211_find_ie() though to simplify the code.
Excellent! I missed it..
> So the loop can be simplified to
>
> el = cfg80211_find_ie(WLAN_EID_DS_PARAMS, el, el_len);
> if (el && el[1] > 0)
> channel = el[2];
I guess el_len should be len, but I got it :)
> You might also invoke this only when you know you're scanning, to avoid
> the overhead otherwise, but with this driver it probably doesn't matter
> much.
Probably it doesn't, but you are right that is useless to waste time
parsing those mgmt frames when not scanning.
I modified the function (and I changed also its name) in a way that
when scanning it avoid parsing and it does return priv->channel, and I
made it also inline.
So this is the updated patch.
If you agree, we could push it for merge :)
Thank you
Andrea
drivers/net/wireless/at76c50x-usb.c | 53 +++++++++++++++++++++++++++++++++++++
drivers/net/wireless/at76c50x-usb.h | 1 +
2 files changed, 54 insertions(+)
diff --git a/drivers/net/wireless/at76c50x-usb.c
b/drivers/net/wireless/at76c50x-usb.c
index 10fd12e..6f52633 100644
--- a/drivers/net/wireless/at76c50x-usb.c
+++ b/drivers/net/wireless/at76c50x-usb.c
@@ -1429,6 +1429,8 @@ static int at76_startup_device(struct at76_priv *priv)
/* remove BSSID from previous run */
memset(priv->bssid, 0, ETH_ALEN);
+ priv->scanning = false;
+
if (at76_set_radio(priv, 1) == 1)
at76_wait_completion(priv, CMD_RADIO_ON);
@@ -1502,6 +1504,52 @@ static void at76_work_submit_rx(struct work_struct *work)
mutex_unlock(&priv->mtx);
}
+/* This is a workaround to make scan working:
+ * currently mac80211 does not process frames with no frequency
+ * information.
+ * However during scan the HW performs a sweep by itself, and we
+ * are unable to know where the radio is actually tuned.
+ * This function tries to do its best to guess this information..
+ * During scan, If the current frame is a beacon or a probe response,
+ * the channel information is extracted from it.
+ * When not scanning, for other frames, or if it happens that for
+ * whatever reason we fail to parse beacons and probe responses, this
+ * function returns the priv->channel information, that should be correct
+ * at least when we are not scanning.
+ */
+static inline int at76_guess_freq(struct at76_priv *priv)
+{
+ size_t el_off;
+ const u8 *el;
+ int channel = priv->channel;
+ int len = priv->rx_skb->len;
+ struct ieee80211_hdr *hdr = (void *)priv->rx_skb->data;
+
+ if (!priv->scanning)
+ goto exit;
+
+ if (len < 24)
+ goto exit;
+
+ if (ieee80211_is_probe_resp(hdr->frame_control)) {
+ el_off = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
+ el = ((struct ieee80211_mgmt *)hdr)->u.probe_resp.variable;
+ } else if (ieee80211_is_beacon(hdr->frame_control)) {
+ el_off = offsetof(struct ieee80211_mgmt, u.beacon.variable);
+ el = ((struct ieee80211_mgmt *)hdr)->u.beacon.variable;
+ } else
+ goto exit;
+
+ len -= el_off;
+
+ el = cfg80211_find_ie(WLAN_EID_DS_PARAMS, el, len);
+ if (el && el[1] > 0)
+ channel = el[2];
+
+exit:
+ return ieee80211_channel_to_frequency(channel, IEEE80211_BAND_2GHZ);
+}
+
static void at76_rx_tasklet(unsigned long param)
{
struct urb *urb = (struct urb *)param;
@@ -1542,6 +1590,8 @@ static void at76_rx_tasklet(unsigned long param)
rx_status.signal = buf->rssi;
rx_status.flag |= RX_FLAG_DECRYPTED;
rx_status.flag |= RX_FLAG_IV_STRIPPED;
+ rx_status.band = IEEE80211_BAND_2GHZ;
+ rx_status.freq = at76_guess_freq(priv);
at76_dbg(DBG_MAC80211, "calling ieee80211_rx_irqsafe(): %d/%d",
priv->rx_skb->len, priv->rx_skb->data_len);
@@ -1894,6 +1944,8 @@ static void at76_dwork_hw_scan(struct work_struct *work)
if (is_valid_ether_addr(priv->bssid))
at76_join(priv);
+ priv->scanning = false;
+
mutex_unlock(&priv->mtx);
ieee80211_scan_completed(priv->hw, false);
@@ -1948,6 +2000,7 @@ static int at76_hw_scan(struct ieee80211_hw *hw,
goto exit;
}
+ priv->scanning = true;
ieee80211_queue_delayed_work(priv->hw, &priv->dwork_hw_scan,
SCAN_POLL_INTERVAL);
diff --git a/drivers/net/wireless/at76c50x-usb.h
b/drivers/net/wireless/at76c50x-usb.h
index 4718aa5..55090a3 100644
--- a/drivers/net/wireless/at76c50x-usb.h
+++ b/drivers/net/wireless/at76c50x-usb.h
@@ -418,6 +418,7 @@ struct at76_priv {
int scan_max_time; /* scan max channel time */
int scan_mode; /* SCAN_TYPE_ACTIVE, SCAN_TYPE_PASSIVE */
int scan_need_any; /* if set, need to scan for any ESSID */
+ bool scanning; /* if set, the scan is running */
u16 assoc_id; /* current association ID, if associated */
--
1.9.1
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