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Date:	Thu, 12 May 2016 12:33:25 -0700
From:	Bjorn Andersson <bjorn.andersson@...aro.org>
To:	Eugene Krasnikov <k.eugene.e@...il.com>,
	Kalle Valo <kvalo@...eaurora.org>,
	Pontus Fuchs <pontus.fuchs@...il.com>, Jouni Malinen <j@...fi>
Cc:	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC] wcn36xx: Implement firmware assisted scan

Using the software based channel scan mechanism from mac80211 keeps us
offline for 10-15 second, we should instead issue a start_scan/end_scan
on each channel reducing this time.

Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
---

With this implementation I see a reduction of throughput for about 1-2 seconds
with iperf while scanning, so the improvement is clear.

The problem with the implementation is that ieee80211_rx_status must specify
the correct band for the core to not drop the beacons. I have searched for
indications in the incoming data, but am not able to find anything useful, so
this currently rely on shared state (scan_freq/scan_band) that gets updated
during scan.

If anyone familiar with this hardware have any suggestions on how to better
deal with this I would appreciate the feedback.

 drivers/net/wireless/ath/wcn36xx/main.c    | 62 ++++++++++++++++++++++++------
 drivers/net/wireless/ath/wcn36xx/smd.c     |  8 ++--
 drivers/net/wireless/ath/wcn36xx/smd.h     |  4 +-
 drivers/net/wireless/ath/wcn36xx/txrx.c    | 19 ++++++---
 drivers/net/wireless/ath/wcn36xx/wcn36xx.h |  9 +++++
 5 files changed, 79 insertions(+), 23 deletions(-)

diff --git a/drivers/net/wireless/ath/wcn36xx/main.c b/drivers/net/wireless/ath/wcn36xx/main.c
index 25a492d7504b..20ff661694ed 100644
--- a/drivers/net/wireless/ath/wcn36xx/main.c
+++ b/drivers/net/wireless/ath/wcn36xx/main.c
@@ -489,23 +489,57 @@ out:
 	return ret;
 }
 
-static void wcn36xx_sw_scan_start(struct ieee80211_hw *hw,
-				  struct ieee80211_vif *vif,
-				  const u8 *mac_addr)
+static void wcn36xx_hw_scan_worker(struct work_struct *work)
 {
-	struct wcn36xx *wcn = hw->priv;
+	struct wcn36xx *wcn = container_of(work, struct wcn36xx, scan_work);
+	struct cfg80211_scan_request *req = wcn->scan_req;
+	u8 channels[WCN36XX_HAL_PNO_MAX_NETW_CHANNELS_EX];
+	int i;
+
+	wcn36xx_dbg(WCN36XX_DBG_MAC, "mac80211 scan %d channels worker\n", req->n_channels);
+
+	for (i = 0; i < req->n_channels; i++)
+		channels[i] = req->channels[i]->hw_value;
+
+	wcn36xx_smd_update_scan_params(wcn, channels, req->n_channels);
 
 	wcn36xx_smd_init_scan(wcn, HAL_SYS_MODE_SCAN);
-	wcn36xx_smd_start_scan(wcn);
+	for (i = 0; i < req->n_channels; i++) {
+		wcn->scan_freq = req->channels[i]->center_freq;
+		wcn->scan_band = req->channels[i]->band;
+
+		wcn36xx_smd_start_scan(wcn, req->channels[i]->hw_value);
+		msleep(30);
+		wcn36xx_smd_end_scan(wcn, req->channels[i]->hw_value);
+
+		wcn->scan_freq = 0;
+	}
+	wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN);
+
+	ieee80211_scan_completed(wcn->hw, false);
+
+	mutex_lock(&wcn->scan_lock);
+	wcn->scan_req = NULL;
+	mutex_unlock(&wcn->scan_lock);
 }
 
-static void wcn36xx_sw_scan_complete(struct ieee80211_hw *hw,
-				     struct ieee80211_vif *vif)
+static int wcn36xx_hw_scan(struct ieee80211_hw *hw,
+			   struct ieee80211_vif *vif,
+			   struct ieee80211_scan_request *hw_req)
 {
 	struct wcn36xx *wcn = hw->priv;
 
-	wcn36xx_smd_end_scan(wcn);
-	wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN);
+	mutex_lock(&wcn->scan_lock);
+	if (wcn->scan_req) {
+		mutex_unlock(&wcn->scan_lock);
+		return -EBUSY;
+	}
+	wcn->scan_req = &hw_req->req;
+	mutex_unlock(&wcn->scan_lock);
+
+	schedule_work(&wcn->scan_work);
+
+	return 0;
 }
 
 static void wcn36xx_update_allowed_rates(struct ieee80211_sta *sta,
@@ -919,8 +953,7 @@ static const struct ieee80211_ops wcn36xx_ops = {
 	.configure_filter       = wcn36xx_configure_filter,
 	.tx			= wcn36xx_tx,
 	.set_key		= wcn36xx_set_key,
-	.sw_scan_start		= wcn36xx_sw_scan_start,
-	.sw_scan_complete	= wcn36xx_sw_scan_complete,
+	.hw_scan		= wcn36xx_hw_scan,
 	.bss_info_changed	= wcn36xx_bss_info_changed,
 	.set_rts_threshold	= wcn36xx_set_rts_threshold,
 	.sta_add		= wcn36xx_sta_add,
@@ -945,6 +978,7 @@ static int wcn36xx_init_ieee80211(struct wcn36xx *wcn)
 	ieee80211_hw_set(wcn->hw, SUPPORTS_PS);
 	ieee80211_hw_set(wcn->hw, SIGNAL_DBM);
 	ieee80211_hw_set(wcn->hw, HAS_RATE_CONTROL);
+	ieee80211_hw_set(wcn->hw, SINGLE_SCAN_ON_ALL_BANDS);
 
 	wcn->hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION) |
 		BIT(NL80211_IFTYPE_AP) |
@@ -954,6 +988,9 @@ static int wcn36xx_init_ieee80211(struct wcn36xx *wcn)
 	wcn->hw->wiphy->bands[IEEE80211_BAND_2GHZ] = &wcn_band_2ghz;
 	wcn->hw->wiphy->bands[IEEE80211_BAND_5GHZ] = &wcn_band_5ghz;
 
+	wcn->hw->wiphy->max_scan_ssids = WCN36XX_MAX_SCAN_SSIDS;
+	wcn->hw->wiphy->max_scan_ie_len = WCN36XX_MAX_SCAN_IE_LEN;
+
 	wcn->hw->wiphy->cipher_suites = cipher_suites;
 	wcn->hw->wiphy->n_cipher_suites = ARRAY_SIZE(cipher_suites);
 
@@ -1074,6 +1111,9 @@ static int wcn36xx_probe(struct platform_device *pdev)
 	wcn->hw = hw;
 	wcn->dev = &pdev->dev;
 	mutex_init(&wcn->hal_mutex);
+	mutex_init(&wcn->scan_lock);
+
+	INIT_WORK(&wcn->scan_work, wcn36xx_hw_scan_worker);
 
 	wcn->smd_channel = qcom_wcnss_open_channel(wcnss, "WLAN_CTRL", wcn36xx_smd_rsp_process);
 	if (IS_ERR(wcn->smd_channel)) {
diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
index 377c4bfb84ee..aa65d8ec7abf 100644
--- a/drivers/net/wireless/ath/wcn36xx/smd.c
+++ b/drivers/net/wireless/ath/wcn36xx/smd.c
@@ -528,7 +528,7 @@ out:
 	return ret;
 }
 
-int wcn36xx_smd_start_scan(struct wcn36xx *wcn)
+int wcn36xx_smd_start_scan(struct wcn36xx *wcn, u8 scan_channel)
 {
 	struct wcn36xx_hal_start_scan_req_msg msg_body;
 	int ret = 0;
@@ -536,7 +536,7 @@ int wcn36xx_smd_start_scan(struct wcn36xx *wcn)
 	mutex_lock(&wcn->hal_mutex);
 	INIT_HAL_MSG(msg_body, WCN36XX_HAL_START_SCAN_REQ);
 
-	msg_body.scan_channel = WCN36XX_HW_CHANNEL(wcn);
+	msg_body.scan_channel = scan_channel;
 
 	PREPARE_HAL_BUF(wcn->hal_buf, msg_body);
 
@@ -558,7 +558,7 @@ out:
 	return ret;
 }
 
-int wcn36xx_smd_end_scan(struct wcn36xx *wcn)
+int wcn36xx_smd_end_scan(struct wcn36xx *wcn, u8 scan_channel)
 {
 	struct wcn36xx_hal_end_scan_req_msg msg_body;
 	int ret = 0;
@@ -566,7 +566,7 @@ int wcn36xx_smd_end_scan(struct wcn36xx *wcn)
 	mutex_lock(&wcn->hal_mutex);
 	INIT_HAL_MSG(msg_body, WCN36XX_HAL_END_SCAN_REQ);
 
-	msg_body.scan_channel = WCN36XX_HW_CHANNEL(wcn);
+	msg_body.scan_channel = scan_channel;
 
 	PREPARE_HAL_BUF(wcn->hal_buf, msg_body);
 
diff --git a/drivers/net/wireless/ath/wcn36xx/smd.h b/drivers/net/wireless/ath/wcn36xx/smd.h
index 82e3b37b669e..e4574c87528a 100644
--- a/drivers/net/wireless/ath/wcn36xx/smd.h
+++ b/drivers/net/wireless/ath/wcn36xx/smd.h
@@ -69,8 +69,8 @@ int wcn36xx_smd_load_nv(struct wcn36xx *wcn);
 int wcn36xx_smd_start(struct wcn36xx *wcn);
 int wcn36xx_smd_stop(struct wcn36xx *wcn);
 int wcn36xx_smd_init_scan(struct wcn36xx *wcn, enum wcn36xx_hal_sys_mode mode);
-int wcn36xx_smd_start_scan(struct wcn36xx *wcn);
-int wcn36xx_smd_end_scan(struct wcn36xx *wcn);
+int wcn36xx_smd_start_scan(struct wcn36xx *wcn, u8 scan_channel);
+int wcn36xx_smd_end_scan(struct wcn36xx *wcn, u8 scan_channel);
 int wcn36xx_smd_finish_scan(struct wcn36xx *wcn,
 			    enum wcn36xx_hal_sys_mode mode);
 int wcn36xx_smd_update_scan_params(struct wcn36xx *wcn, u8 *channels, size_t channel_count);
diff --git a/drivers/net/wireless/ath/wcn36xx/txrx.c b/drivers/net/wireless/ath/wcn36xx/txrx.c
index 9bec8237231d..1754027d6500 100644
--- a/drivers/net/wireless/ath/wcn36xx/txrx.c
+++ b/drivers/net/wireless/ath/wcn36xx/txrx.c
@@ -45,9 +45,20 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
 	skb_put(skb, bd->pdu.mpdu_header_off + bd->pdu.mpdu_len);
 	skb_pull(skb, bd->pdu.mpdu_header_off);
 
+	hdr = (struct ieee80211_hdr *) skb->data;
+	fc = __le16_to_cpu(hdr->frame_control);
+	sn = IEEE80211_SEQ_TO_SN(__le16_to_cpu(hdr->seq_ctrl));
+
+	/* When scanning associate beacons to this */
+	if (ieee80211_is_beacon(hdr->frame_control) && wcn->scan_freq) {
+		status.freq = wcn->scan_freq;
+		status.band = wcn->scan_band;
+	} else {
+		status.freq = WCN36XX_CENTER_FREQ(wcn);
+		status.band = WCN36XX_BAND(wcn);
+	}
+
 	status.mactime = 10;
-	status.freq = WCN36XX_CENTER_FREQ(wcn);
-	status.band = WCN36XX_BAND(wcn);
 	status.signal = -get_rssi0(bd);
 	status.antenna = 1;
 	status.rate_idx = 1;
@@ -61,10 +72,6 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
 
 	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
 
-	hdr = (struct ieee80211_hdr *) skb->data;
-	fc = __le16_to_cpu(hdr->frame_control);
-	sn = IEEE80211_SEQ_TO_SN(__le16_to_cpu(hdr->seq_ctrl));
-
 	if (ieee80211_is_beacon(hdr->frame_control)) {
 		wcn36xx_dbg(WCN36XX_DBG_BEACON, "beacon skb %p len %d fc %04x sn %d\n",
 			    skb, skb->len, fc, sn);
diff --git a/drivers/net/wireless/ath/wcn36xx/wcn36xx.h b/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
index 38d55804ffaf..45d2db99e12c 100644
--- a/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
+++ b/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
@@ -35,6 +35,9 @@
 /* How many frames until we start a-mpdu TX session */
 #define WCN36XX_AMPDU_START_THRESH	20
 
+#define WCN36XX_MAX_SCAN_SSIDS		9
+#define WCN36XX_MAX_SCAN_IE_LEN		500
+
 extern unsigned int wcn36xx_dbg_mask;
 
 enum wcn36xx_debug_mask {
@@ -212,6 +215,12 @@ struct wcn36xx {
 	spinlock_t		hal_ind_lock;
 	struct list_head	hal_ind_queue;
 
+	struct work_struct	scan_work;
+	struct cfg80211_scan_request *scan_req;
+	int			scan_freq;
+	int			scan_band;
+	struct mutex		scan_lock;
+
 	/* DXE channels */
 	struct wcn36xx_dxe_ch	dxe_tx_l_ch;	/* TX low */
 	struct wcn36xx_dxe_ch	dxe_tx_h_ch;	/* TX high */
-- 
2.5.0

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