mac80211: support hw scan while idle

Currently, mac80211 goes to idle-off before starting a scan.
However, some devices that implement hw scan might not
need going idle-off in order to perform a hw scan, and
thus saving some energy and simplifying their state machine.

(Note that this is also the case for sched scan - it
currently doesn't make mac80211 go idle-off)

Add a new flag to indicate support for hw scan while idle.
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -1164,6 +1164,10 @@ enum sta_notify_cmd {
  * @IEEE80211_HW_TX_AMPDU_SETUP_IN_HW: The device handles TX A-MPDU session
  *	setup strictly in HW. mac80211 should not attempt to do this in
  *	software.
+ *
+ * @IEEE80211_HW_SCAN_WHILE_IDLE: The device can do hw scan while
+ *	being idle (i.e. mac80211 doesn't have to go idle-off during the
+ *	the scan).
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_HAS_RATE_CONTROL			= 1<<0,
@@ -1190,6 +1194,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_PER_STA_GTK		= 1<<21,
 	IEEE80211_HW_AP_LINK_PS				= 1<<22,
 	IEEE80211_HW_TX_AMPDU_SETUP_IN_HW		= 1<<23,
+	IEEE80211_HW_SCAN_WHILE_IDLE			= 1<<24,
 };
 
 /**

net/mac80211/debugfs.c

@@ -263,6 +263,8 @@ static ssize_t hwflags_read(struct file *file, char __user *user_buf,
 		sf += snprintf(buf + sf, mxln - sf, "AP_LINK_PS\n");
 	if (local->hw.flags & IEEE80211_HW_TX_AMPDU_SETUP_IN_HW)
 		sf += snprintf(buf + sf, mxln - sf, "TX_AMPDU_SETUP_IN_HW\n");
+	if (local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)
+		sf += snprintf(buf + sf, mxln - sf, "SCAN_WHILE_IDLE\n");
 
 	rv = simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
 	kfree(buf);

net/mac80211/iface.c

@@ -1332,7 +1332,8 @@ u32 __ieee80211_recalc_idle(struct ieee80211_local *local)
 		wk->sdata->vif.bss_conf.idle = false;
 	}
 
-	if (local->scan_sdata) {
+	if (local->scan_sdata &&
+	    !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
 		scanning = true;
 		local->scan_sdata->vif.bss_conf.idle = false;
 	}

net/mac80211/main.c

@@ -697,6 +697,9 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	    )
 		return -EINVAL;
 
+	if ((hw->flags & IEEE80211_HW_SCAN_WHILE_IDLE) && !local->ops->hw_scan)
+		return -EINVAL;
+
 	if (hw->max_report_rates == 0)
 		hw->max_report_rates = hw->max_rates;