[RFC] wcn36xx: Implement firmware assisted scan

From: Bjorn Andersson
Date: Thu May 12 2016 - 15:33:35 EST

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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@xxxxxxxxxx>
---

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

Next message: Doug Ledford: "Re: [PATCH net-next 2/5] drivers: replace dev->trans_start accesses with dev_trans_start"
Previous message: Abhishek Sahu: "Re: [PATCH 1/2] i2c: qup: Cleared the error bits in ISR"
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