Less important now, given Loic's breakthrough with FW scan offload on
5GHz channels, but downstream does do software scanning so these fixes
for that path may still be valuable to someone.
Benjamin Li (3):
wcn36xx: add debug prints for sw_scan start/complete
wcn36xx: implement flush op to speed up connected scan
wcn36xx: ensure pairing of init_scan/finish_scan and
start_scan/end_scan
drivers/net/wireless/ath/wcn36xx/dxe.c | 47 +++++++++++++++++++++
drivers/net/wireless/ath/wcn36xx/dxe.h | 1 +
drivers/net/wireless/ath/wcn36xx/main.c | 49 ++++++++++++++++++----
drivers/net/wireless/ath/wcn36xx/smd.c | 4 ++
drivers/net/wireless/ath/wcn36xx/wcn36xx.h | 1 +
5 files changed, 95 insertions(+), 7 deletions(-)
--
2.25.1
Without ieee80211_ops->flush implemented to empty HW queues, mac80211 will
do a 100ms dead wait after stopping SW queues, before leaving the operating
channel to resume a software connected scan[1].
(see ieee80211_scan_state_resume)
This wait is correctly included in the calculation for whether or not
we've exceeded max off-channel time, as it occurs after sending the null
frame with PS bit set. Thus, with 125 ms max off-channel time we only
have 25 ms of scan time, which technically isn't even enough to scan one
channel (although mac80211 always scans at least one channel per off-
channel window).
Moreover, for passive probes we end up spending at least 100 ms + 111 ms
(IEEE80211_PASSIVE_CHANNEL_TIME) "off-channel"[2], which exceeds the listen
interval of 200 ms that we provide in our association request frame. That's
technically out-of-spec.
[1]: Until recently, wcn36xx performed software (rather than FW-offloaded)
scanning when 5GHz channels are requested. This apparent limitation is now
resolved -- see commit 1395f8a6a4d5 ("wcn36xx: Enable hardware scan offload
for 5Ghz band").
[2]: in quotes because about 100 ms of it is still on-channel but with PS
set
Signed-off-by: Benjamin Li <[email protected]>
---
drivers/net/wireless/ath/wcn36xx/dxe.c | 47 +++++++++++++++++++++++++
drivers/net/wireless/ath/wcn36xx/dxe.h | 1 +
drivers/net/wireless/ath/wcn36xx/main.c | 11 ++++++
3 files changed, 59 insertions(+)
diff --git a/drivers/net/wireless/ath/wcn36xx/dxe.c b/drivers/net/wireless/ath/wcn36xx/dxe.c
index 8e1dbfda65386..c4e9e939d7d6d 100644
--- a/drivers/net/wireless/ath/wcn36xx/dxe.c
+++ b/drivers/net/wireless/ath/wcn36xx/dxe.c
@@ -831,6 +831,53 @@ int wcn36xx_dxe_tx_frame(struct wcn36xx *wcn,
return ret;
}
+static bool _wcn36xx_dxe_tx_channel_is_empty(struct wcn36xx_dxe_ch *ch)
+{
+ int flags;
+ struct wcn36xx_dxe_ctl *ctl_bd_start, *ctl_skb_start;
+ struct wcn36xx_dxe_ctl *ctl_bd, *ctl_skb;
+ bool ret = true;
+
+ spin_lock_irqsave(&ch->lock, flags);
+
+ /* Loop through ring buffer looking for nonempty entries. */
+ ctl_bd_start = ch->head_blk_ctl;
+ ctl_bd = ctl_bd_start;
+ ctl_skb_start = ctl_bd_start->next;
+ ctl_skb = ctl_skb_start;
+ do {
+ if (ctl_skb->skb) {
+ ret = false;
+ goto unlock;
+ }
+ ctl_bd = ctl_skb->next;
+ ctl_skb = ctl_bd->next;
+ } while (ctl_skb != ctl_skb_start);
+
+unlock:
+ spin_unlock_irqrestore(&ch->lock, flags);
+ return ret;
+}
+
+int wcn36xx_dxe_tx_flush(struct wcn36xx *wcn)
+{
+ int i = 0;
+
+ /* Called with mac80211 queues stopped. Wait for empty HW queues. */
+ do {
+ if (_wcn36xx_dxe_tx_channel_is_empty(&wcn->dxe_tx_l_ch) &&
+ _wcn36xx_dxe_tx_channel_is_empty(&wcn->dxe_tx_h_ch)) {
+ return 0;
+ }
+ /* This ieee80211_ops callback is specifically allowed to
+ * sleep.
+ */
+ usleep_range(1000, 1100);
+ } while (++i < 100);
+
+ return -EBUSY;
+}
+
int wcn36xx_dxe_init(struct wcn36xx *wcn)
{
int reg_data = 0, ret;
diff --git a/drivers/net/wireless/ath/wcn36xx/dxe.h b/drivers/net/wireless/ath/wcn36xx/dxe.h
index 31b81b7547a32..26a31edf52e99 100644
--- a/drivers/net/wireless/ath/wcn36xx/dxe.h
+++ b/drivers/net/wireless/ath/wcn36xx/dxe.h
@@ -466,5 +466,6 @@ int wcn36xx_dxe_tx_frame(struct wcn36xx *wcn,
struct wcn36xx_tx_bd *bd,
struct sk_buff *skb,
bool is_low);
+int wcn36xx_dxe_tx_flush(struct wcn36xx *wcn);
void wcn36xx_dxe_tx_ack_ind(struct wcn36xx *wcn, u32 status);
#endif /* _DXE_H_ */
diff --git a/drivers/net/wireless/ath/wcn36xx/main.c b/drivers/net/wireless/ath/wcn36xx/main.c
index 81ac86eeaf60b..24bfb30a30f31 100644
--- a/drivers/net/wireless/ath/wcn36xx/main.c
+++ b/drivers/net/wireless/ath/wcn36xx/main.c
@@ -1275,6 +1275,16 @@ static void wcn36xx_ipv6_addr_change(struct ieee80211_hw *hw,
}
#endif
+static void wcn36xx_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+ u32 queues, bool drop)
+{
+ struct wcn36xx *wcn = hw->priv;
+
+ if (wcn36xx_dxe_tx_flush(wcn)) {
+ wcn36xx_err("Failed to flush hardware tx queues\n");
+ }
+}
+
static const struct ieee80211_ops wcn36xx_ops = {
.start = wcn36xx_start,
.stop = wcn36xx_stop,
@@ -1302,6 +1312,7 @@ static const struct ieee80211_ops wcn36xx_ops = {
#if IS_ENABLED(CONFIG_IPV6)
.ipv6_addr_change = wcn36xx_ipv6_addr_change,
#endif
+ .flush = wcn36xx_flush,
CFG80211_TESTMODE_CMD(wcn36xx_tm_cmd)
};
--
2.25.1