Commit aea38272 authored by Felix Fietkau's avatar Felix Fietkau Committed by Kalle Valo
Browse files

mt76: fix beacon timer drift 



The beacon timer drifts by 1 microsecond every TBTT. After 20 minutes
with a beacon interval of 100, the drift will be almost 12 ms, enough to
cause weird issues for devices in powersave mode.

Since the beacon timer is configured in units of 1/16 TU (64 us), we
need to adjust it once every 64 beacons and only for one beacon.

Signed-off-by: default avatarFelix Fietkau <nbd@nbd.name>
Signed-off-by: default avatarKalle Valo <kvalo@codeaurora.org>
parent 81454b84

drivers/net/wireless/mediatek/mt76/mt76x2.h

+4 −1
Original line number Diff line number Diff line
@@ -120,10 +120,13 @@ struct mt76x2_dev { 
	u8 beacon_mask;

	u8 beacon_data_mask;



	u32 rxfilter;

	u8 tbtt_count;

	u16 beacon_int;



	u16 chainmask;



	u32 rxfilter;



	struct mt76x2_calibration cal;



	s8 target_power;

drivers/net/wireless/mediatek/mt76/mt76x2_main.c

+4 −1
Original line number Diff line number Diff line
@@ -238,10 +238,13 @@ mt76x2_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif, 
	if (changed & BSS_CHANGED_BSSID)

		mt76x2_mac_set_bssid(dev, mvif->idx, info->bssid);



	if (changed & BSS_CHANGED_BEACON_INT)

	if (changed & BSS_CHANGED_BEACON_INT) {

		mt76_rmw_field(dev, MT_BEACON_TIME_CFG,

			       MT_BEACON_TIME_CFG_INTVAL,

			       info->beacon_int << 4);

		dev->beacon_int = info->beacon_int;

		dev->tbtt_count = 0;

	}



	if (changed & BSS_CHANGED_BEACON_ENABLED) {

		tasklet_disable(&dev->pre_tbtt_tasklet);

drivers/net/wireless/mediatek/mt76/mt76x2_tx.c

+33 −0
Original line number Diff line number Diff line
@@ -218,6 +218,37 @@ mt76x2_add_buffered_bc(void *priv, u8 *mac, struct ieee80211_vif *vif) 
	data->tail[mvif->idx] = skb;

}



static void

mt76x2_resync_beacon_timer(struct mt76x2_dev *dev)

{

	u32 timer_val = dev->beacon_int << 4;



	dev->tbtt_count++;



	/*

	 * Beacon timer drifts by 1us every tick, the timer is configured

	 * in 1/16 TU (64us) units.

	 */

	if (dev->tbtt_count < 62)

		return;



	if (dev->tbtt_count >= 64) {

		dev->tbtt_count = 0;

		return;

	}



	/*

	 * The updated beacon interval takes effect after two TBTT, because

	 * at this point the original interval has already been loaded into

	 * the next TBTT_TIMER value

	 */

	if (dev->tbtt_count == 62)

		timer_val -= 1;



	mt76_rmw_field(dev, MT_BEACON_TIME_CFG,

		       MT_BEACON_TIME_CFG_INTVAL, timer_val);

}



void mt76x2_pre_tbtt_tasklet(unsigned long arg)

{

	struct mt76x2_dev *dev = (struct mt76x2_dev *) arg;
@@ -226,6 +257,8 @@ void mt76x2_pre_tbtt_tasklet(unsigned long arg) 
	struct sk_buff *skb;

	int i, nframes;



	mt76x2_resync_beacon_timer(dev);



	data.dev = dev;

	__skb_queue_head_init(&data.q);

CRA Git | Maintained and supported by SUSTech CRA and CCSE