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: Felix Fietkau <nbd@xxxxxxxx>
---
drivers/net/wireless/mediatek/mt76/mt76x2.h | 5 ++-
.../net/wireless/mediatek/mt76/mt76x2_main.c | 5 ++-
.../net/wireless/mediatek/mt76/mt76x2_tx.c | 33 +++++++++++++++++++
3 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2.h b/drivers/net/wireless/mediatek/mt76/mt76x2.h
index dc12bbdbb2ee..06ca5a77dfdf 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2.h
@@ -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;
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_main.c b/drivers/net/wireless/mediatek/mt76/mt76x2_main.c
index ce90ff999b49..e4e41faf6739 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_main.c
@@ -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);
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_tx.c b/drivers/net/wireless/mediatek/mt76/mt76x2_tx.c
index e46eafc4c436..560376dd1133 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_tx.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_tx.c
@@ -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);
--
2.17.0
