p54: re-enable power save feature

This patch re-enables p54's power save features and adds a workaround
which temporarily alters the device's power state in order to allow
ps-polls to be sent and buffered data to be retrieved during psm.

(Incorporates patch originally posted as "p54: fix beacon template dtim
IE corruption". -- JWL)

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 6426d2cae6de..01eadb1683fa 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -288,6 +288,45 @@ static int p54_rssi_to_dbm(struct p54_common *priv, int rssi)
                          priv->rssical_db[band].add) / 4;
 }
 
+/*
+ * Even if the firmware is capable of dealing with incoming traffic,
+ * while dozing, we have to prepared in case mac80211 uses PS-POLL
+ * to retrieve outstanding frames from our AP.
+ * (see comment in net/mac80211/mlme.c @ line 1993)
+ */
+static void p54_pspoll_workaround(struct p54_common *priv, struct sk_buff *skb)
+{
+        struct ieee80211_hdr *hdr = (void *) skb->data;
+        struct ieee80211_tim_ie *tim_ie;
+        u8 *tim;
+        u8 tim_len;
+        bool new_psm;
+
+        /* only beacons have a TIM IE */
+        if (!ieee80211_is_beacon(hdr->frame_control))
+                return;
+
+        if (!priv->aid)
+                return;
+
+        /* only consider beacons from the associated BSSID */
+        if (compare_ether_addr(hdr->addr3, priv->bssid))
+                return;
+
+        tim = p54_find_ie(skb, WLAN_EID_TIM);
+        if (!tim)
+                return;
+
+        tim_len = tim[1];
+        tim_ie = (struct ieee80211_tim_ie *) &tim[2];
+
+        new_psm = ieee80211_check_tim(tim_ie, tim_len, priv->aid);
+        if (new_psm != priv->powersave_override) {
+                priv->powersave_override = new_psm;
+                p54_set_ps(priv);
+        }
+}
+
 static int p54_rx_data(struct p54_common *priv, struct sk_buff *skb)
 {
         struct p54_rx_data *hdr = (struct p54_rx_data *) skb->data;
@@ -340,6 +379,9 @@ static int p54_rx_data(struct p54_common *priv, struct sk_buff *skb)
 
         skb_pull(skb, header_len);
         skb_trim(skb, le16_to_cpu(hdr->len));
+        if (unlikely(priv->hw->conf.flags & IEEE80211_CONF_PS))
+                p54_pspoll_workaround(priv, skb);
+
         ieee80211_rx_irqsafe(priv->hw, skb);
 
         queue_delayed_work(priv->hw->workqueue, &priv->work,