* [PATCH rtw-next v7 1/3] wifi: rtw88: download the beacon the reserved page was built with
2026-10-20 20:47 [PATCH rtw-next v7 0/3] wifi: rtw88: channel switch in AP mode Mehmet Fide
@ 2026-10-20 20:47 ` Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 2/3] wifi: rtw88: support channel switch in AP mode Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 3/3] wifi: rtw88: time the countdown downloads from the TBTT Mehmet Fide
2 siblings, 0 replies; 4+ messages in thread
From: Mehmet Fide @ 2026-10-20 20:47 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
rtw_fw_download_rsvd_page() downloads the beacon twice: once as part of
the reserved page and once more on its own, so that the firmware ends up
with a TX descriptor that describes the beacon rather than the whole
page. The second download fetched a new beacon from mac80211 instead of
downloading the one the page already holds.
Besides the extra work, every beacon fetch advances the DTIM count and,
while a channel switch is announced, the CSA countdown; doing it twice
per update lets a countdown that starts at 2 reach 0, which mac80211
warns about. Hand the beacon skb out of the page build and download
that. The hw scan, which downloads the beacon without a page build,
keeps fetching its own.
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
Reviewed-by: Luka Gejak <luka.gejak@linux.dev>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
---
Notes:
Changes in v7:
- none, rebased on rtw-next
Changes in v6:
- none
Changes in v5:
- none
Changes in v4:
- none, rebased on rtw-next
Changes in v3:
- the beacon out-pointer is initialised in the caller
drivers/net/wireless/realtek/rtw88/fw.c | 34 +++++++++++++++----------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 945fedcd375b..3cd17a3bb494 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -1622,7 +1622,8 @@ static int __rtw_build_rsvd_page_from_vifs(struct rtw_dev *rtwdev)
return 0;
}
-static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
+static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size,
+ struct sk_buff **beacon)
{
const struct rtw_chip_info *chip = rtwdev->chip;
struct ieee80211_hw *hw = rtwdev->hw;
@@ -1702,13 +1703,15 @@ static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
list_for_each_entry(rsvd_pkt, &rtwdev->rsvd_page_list, build_list) {
rtw_rsvd_page_list_to_buf(rtwdev, page_size, page_margin,
page, buf, rsvd_pkt);
- if (page == 0)
+ if (page == 0) {
page += rtw_len_to_page(rsvd_pkt->skb->len +
tx_desc_sz, page_size);
- else
+ /* the caller downloads it once more on its own */
+ *beacon = rsvd_pkt->skb;
+ } else {
page += rtw_len_to_page(rsvd_pkt->skb->len, page_size);
-
- kfree_skb(rsvd_pkt->skb);
+ kfree_skb(rsvd_pkt->skb);
+ }
rsvd_pkt->skb = NULL;
}
@@ -1723,11 +1726,12 @@ static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
return NULL;
}
-static int rtw_download_beacon(struct rtw_dev *rtwdev)
+/* the beacon the page was built with, or a fresh one for the hw scan */
+static int rtw_download_beacon(struct rtw_dev *rtwdev, struct sk_buff *beacon)
{
struct ieee80211_hw *hw = rtwdev->hw;
struct rtw_rsvd_page *rsvd_pkt;
- struct sk_buff *skb;
+ struct sk_buff *skb = beacon;
int ret = 0;
rsvd_pkt = list_first_entry_or_null(&rtwdev->rsvd_page_list,
@@ -1744,7 +1748,8 @@ static int rtw_download_beacon(struct rtw_dev *rtwdev)
return -EINVAL;
}
- skb = rtw_get_rsvd_page_skb(hw, rsvd_pkt);
+ if (!skb)
+ skb = rtw_get_rsvd_page_skb(hw, rsvd_pkt);
if (!skb) {
rtw_err(rtwdev, "failed to get beacon skb\n");
return -ENOMEM;
@@ -1754,18 +1759,20 @@ static int rtw_download_beacon(struct rtw_dev *rtwdev)
if (ret)
rtw_err(rtwdev, "failed to download drv rsvd page\n");
- dev_kfree_skb(skb);
+ if (!beacon)
+ dev_kfree_skb(skb);
return ret;
}
int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
{
- u8 *buf;
+ struct sk_buff *beacon = NULL;
u32 size;
+ u8 *buf;
int ret;
- buf = rtw_build_rsvd_page(rtwdev, &size);
+ buf = rtw_build_rsvd_page(rtwdev, &size, &beacon);
if (!buf) {
rtw_err(rtwdev, "failed to build rsvd page pkt\n");
return -ENOMEM;
@@ -1782,13 +1789,14 @@ int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
* the beacon again to replace the TX desc header, and we will get
* a correct tx_desc for the beacon in the rsvd page.
*/
- ret = rtw_download_beacon(rtwdev);
+ ret = rtw_download_beacon(rtwdev, beacon);
if (ret) {
rtw_err(rtwdev, "failed to download beacon\n");
goto free;
}
free:
+ dev_kfree_skb(beacon);
kfree(buf);
return ret;
@@ -2345,7 +2353,7 @@ int rtw_hw_scan_offload(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
rtw_fw_set_scan_offload(rtwdev, &cs_option, rtwvif, &chan_list);
out:
if (rtwdev->ap_active) {
- ret = rtw_download_beacon(rtwdev);
+ ret = rtw_download_beacon(rtwdev, NULL);
if (ret)
rtw_err(rtwdev, "HW scan download beacon failed\n");
}
--
2.55.0
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH rtw-next v7 2/3] wifi: rtw88: support channel switch in AP mode
2026-10-20 20:47 [PATCH rtw-next v7 0/3] wifi: rtw88: channel switch in AP mode Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 1/3] wifi: rtw88: download the beacon the reserved page was built with Mehmet Fide
@ 2026-10-20 20:47 ` Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 3/3] wifi: rtw88: time the countdown downloads from the TBTT Mehmet Fide
2 siblings, 0 replies; 4+ messages in thread
From: Mehmet Fide @ 2026-10-20 20:47 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
hostapd's CHAN_SWITCH is refused because the driver does not announce
channel switch support, so an rtw88 AP can only change its channel by
being torn down and started again.
Declare WIPHY_FLAG_HAS_CHANNEL_SWITCH and implement
channel_switch_beacon: the firmware repeats the beacon held in the
first reserved page, so while a switch is announced the page is
downloaded again every beacon interval to advance the countdown, and
ieee80211_csa_finish() is called once it completes. IBSS shares the
page and the work.
The work is a delayed work of the device and csa_vif names the
interface, both under the driver mutex. The countdown is cancelled when
the AP stops, when the interface goes away, on WoWLAN suspend and in
rtw_core_stop(); the BSS_CHANGED_BEACON replay after a hardware restart
resumes it. The other page downloads during a countdown, the TIM update,
the PG backup and the one on association, are skipped until the beacon
after the switch, since every beacon fetch advances the countdown; the
next download carries their changes. A scan is refused: it would take
the AP off the channel its stations count down to.
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
Notes:
Changes in v7:
- csa_vif is kept until the beacon after the switch: a TIM update
before it fetched one beacon past count 1 and hit the WARN in
ieee80211_beacon_update_cntdwn()
- rebased on rtw-next
Changes in v6:
- the countdown work is an ieee80211 delayed work under the driver
mutex, csa_vif is driver state under the mutex; no wiphy lock in
rtw88 (Ping-Ke)
- rtw_core_stop() cancels the work and clears csa_vif, which covers the
IPS path and the firmware recovery (Ping-Ke)
- the downloads are paced from the first one with an absolute due time:
queued after each download, the countdown drifted by about 10 ms per
beacon interval on the ordered mac80211 workqueue, and a station
switched ahead of the AP on a count of 50
- the BSS_CHANGED_BEACON path says why it starts the countdown (the
replay after a hardware restart) and stops it when the beacon comes
back without a switch announced (Ping-Ke)
Changes in v5:
- rtw_fw_csa_active/start/stop() assert the wiphy lock
- hw_scan() takes the mutex with guard()
- the ASSOC path says why it skips the download: the STA+AP combination
Changes in v4:
- the work and csa_vif live in rtw_dev; no lookup through the reserved page
- the countdown is stopped before a firmware recovery restarts the hardware
- a scan is refused while a switch is announced
- one beacon fetch per interval during the countdown
drivers/net/wireless/realtek/rtw88/fw.c | 80 ++++++++++++++++++-
drivers/net/wireless/realtek/rtw88/fw.h | 4 +
drivers/net/wireless/realtek/rtw88/mac80211.c | 39 +++++++--
drivers/net/wireless/realtek/rtw88/main.c | 6 +-
drivers/net/wireless/realtek/rtw88/main.h | 3 +
5 files changed, 124 insertions(+), 8 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 3cd17a3bb494..2d81aaeed0d7 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -1802,14 +1802,90 @@ int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
return ret;
}
+bool rtw_fw_csa_active(struct rtw_dev *rtwdev)
+{
+ lockdep_assert_held(&rtwdev->mutex);
+
+ return !!rtwdev->csa_vif;
+}
+
+/* paced from the first download: a late one does not delay the next */
+static void rtw_fw_csa_queue(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+ u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+ s64 delay;
+
+ rtwdev->csa_due = ktime_add_us(rtwdev->csa_due, interval);
+ delay = ktime_us_delta(rtwdev->csa_due, ktime_get());
+ ieee80211_queue_delayed_work(rtwdev->hw, &rtwdev->csa_beacon_work,
+ usecs_to_jiffies(max(delay, 0)));
+}
+
+void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+ lockdep_assert_held(&rtwdev->mutex);
+
+ if (rtwdev->csa_vif == vif)
+ return;
+
+ rtwdev->csa_vif = vif;
+ rtwdev->csa_due = ktime_get();
+ rtw_fw_csa_queue(rtwdev, vif);
+}
+
+void rtw_fw_csa_stop(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+ lockdep_assert_held(&rtwdev->mutex);
+
+ if (!vif || rtwdev->csa_vif != vif)
+ return;
+
+ rtwdev->csa_vif = NULL;
+ cancel_delayed_work(&rtwdev->csa_beacon_work);
+}
+
void rtw_fw_update_beacon_work(struct work_struct *work)
{
struct rtw_dev *rtwdev = container_of(work, struct rtw_dev,
update_beacon_work);
mutex_lock(&rtwdev->mutex);
- rtw_fw_download_rsvd_page(rtwdev);
- rtw_send_rsvd_page_h2c(rtwdev);
+
+ /* a fetch advances the countdown, the next download carries the TIM */
+ if (!rtw_fw_csa_active(rtwdev)) {
+ rtw_fw_download_rsvd_page(rtwdev);
+ rtw_send_rsvd_page_h2c(rtwdev);
+ }
+
+ mutex_unlock(&rtwdev->mutex);
+}
+
+void rtw_fw_csa_beacon_work(struct work_struct *work)
+{
+ struct rtw_dev *rtwdev = container_of(work, struct rtw_dev,
+ csa_beacon_work.work);
+ struct ieee80211_vif *vif;
+
+ mutex_lock(&rtwdev->mutex);
+
+ vif = rtwdev->csa_vif;
+ if (!vif)
+ goto out;
+
+ if (!vif->bss_conf.csa_active) {
+ rtwdev->csa_vif = NULL;
+ goto out;
+ }
+
+ if (!ieee80211_beacon_cntdwn_is_complete(vif, 0)) {
+ rtw_fw_download_rsvd_page(rtwdev);
+ rtw_send_rsvd_page_h2c(rtwdev);
+ rtw_fw_csa_queue(rtwdev, vif);
+ } else {
+ ieee80211_csa_finish(vif, 0);
+ }
+
+out:
mutex_unlock(&rtwdev->mutex);
}
diff --git a/drivers/net/wireless/realtek/rtw88/fw.h b/drivers/net/wireless/realtek/rtw88/fw.h
index 48ad9ceab6ea..d8e58e4ed836 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.h
+++ b/drivers/net/wireless/realtek/rtw88/fw.h
@@ -863,7 +863,11 @@ void rtw_add_rsvd_page_pno(struct rtw_dev *rtwdev,
void rtw_add_rsvd_page_sta(struct rtw_dev *rtwdev,
struct rtw_vif *rtwvif);
int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev);
+bool rtw_fw_csa_active(struct rtw_dev *rtwdev);
+void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif);
+void rtw_fw_csa_stop(struct rtw_dev *rtwdev, struct ieee80211_vif *vif);
void rtw_fw_update_beacon_work(struct work_struct *work);
+void rtw_fw_csa_beacon_work(struct work_struct *work);
void rtw_send_rsvd_page_h2c(struct rtw_dev *rtwdev);
int rtw_dump_drv_rsvd_page(struct rtw_dev *rtwdev,
u32 offset, u32 size, u32 *buf);
diff --git a/drivers/net/wireless/realtek/rtw88/mac80211.c b/drivers/net/wireless/realtek/rtw88/mac80211.c
index 2a9b09fa76e7..182aecc76820 100644
--- a/drivers/net/wireless/realtek/rtw88/mac80211.c
+++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
@@ -237,6 +237,8 @@ static void rtw_ops_remove_interface(struct ieee80211_hw *hw,
mutex_lock(&rtwdev->mutex);
+ rtw_fw_csa_stop(rtwdev, vif);
+
rtw_leave_lps_deep(rtwdev);
rtw_txq_cleanup(rtwdev, vif->txq);
@@ -395,8 +397,11 @@ static void rtw_ops_bss_info_changed(struct ieee80211_hw *hw,
if (vif->cfg.assoc) {
rtw_coex_connect_notify(rtwdev, COEX_ASSOCIATE_FINISH);
- rtw_fw_download_rsvd_page(rtwdev);
- rtw_send_rsvd_page_h2c(rtwdev);
+ /* a station associating while the AP counts down */
+ if (!rtw_fw_csa_active(rtwdev)) {
+ rtw_fw_download_rsvd_page(rtwdev);
+ rtw_send_rsvd_page_h2c(rtwdev);
+ }
rtw_fw_default_port(rtwdev, rtwvif);
rtw_coex_media_status_notify(rtwdev, vif->cfg.assoc);
if (rtw_bf_support)
@@ -438,6 +443,11 @@ static void rtw_ops_bss_info_changed(struct ieee80211_hw *hw,
rtw_set_dtim_period(rtwdev, conf->dtim_period);
rtw_fw_download_rsvd_page(rtwdev);
rtw_send_rsvd_page_h2c(rtwdev);
+ /* restart replay resumes it, a beacon without CSA ends it */
+ if (conf->csa_active)
+ rtw_fw_csa_start(rtwdev, vif);
+ else
+ rtw_fw_csa_stop(rtwdev, vif);
}
if (changed & BSS_CHANGED_BEACON_ENABLED) {
@@ -490,6 +500,7 @@ static void rtw_ops_stop_ap(struct ieee80211_hw *hw,
struct rtw_dev *rtwdev = hw->priv;
mutex_lock(&rtwdev->mutex);
+ rtw_fw_csa_stop(rtwdev, vif);
rtw_write32_clr(rtwdev, REG_TCR, BIT_TCR_UPDATE_HGQMD);
rtw_write16(rtwdev, REG_ATIMWND, ATIMWND_DEFAULT);
rtwdev->ap_active = false;
@@ -556,6 +567,17 @@ static int rtw_ops_set_tim(struct ieee80211_hw *hw, struct ieee80211_sta *sta,
return 0;
}
+static void rtw_ops_channel_switch_beacon(struct ieee80211_hw *hw,
+ struct ieee80211_vif *vif,
+ struct cfg80211_chan_def *chandef)
+{
+ struct rtw_dev *rtwdev = hw->priv;
+
+ mutex_lock(&rtwdev->mutex);
+ rtw_fw_csa_start(rtwdev, vif);
+ mutex_unlock(&rtwdev->mutex);
+}
+
static int rtw_ops_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
struct ieee80211_vif *vif, struct ieee80211_sta *sta,
struct ieee80211_key_conf *key)
@@ -626,7 +648,8 @@ static int rtw_ops_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
}
/* download new cam settings for PG to backup */
- if (rtw_get_lps_deep_mode(rtwdev) == LPS_DEEP_MODE_PG)
+ if (rtw_get_lps_deep_mode(rtwdev) == LPS_DEEP_MODE_PG &&
+ !rtw_fw_csa_active(rtwdev))
rtw_fw_download_rsvd_page(rtwdev);
out:
@@ -846,6 +869,7 @@ static int rtw_ops_suspend(struct ieee80211_hw *hw,
int ret;
mutex_lock(&rtwdev->mutex);
+ rtw_fw_csa_stop(rtwdev, rtwdev->csa_vif);
ret = rtw_wow_suspend(rtwdev, wowlan);
if (ret)
rtw_err(rtwdev, "failed to suspend for wow %d\n", ret);
@@ -893,20 +917,24 @@ static int rtw_ops_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
struct rtw_dev *rtwdev = hw->priv;
int ret;
+ guard(mutex)(&rtwdev->mutex);
+
+ /* a scan takes the AP off the channel its stations count down to */
+ if (rtw_fw_csa_active(rtwdev))
+ return -EBUSY;
+
if (!rtw_fw_feature_check(&rtwdev->fw, FW_FEATURE_SCAN_OFFLOAD))
return 1;
if (test_bit(RTW_FLAG_SCANNING, rtwdev->flags))
return -EBUSY;
- mutex_lock(&rtwdev->mutex);
rtw_hw_scan_start(rtwdev, vif, req);
ret = rtw_hw_scan_offload(rtwdev, vif, true);
if (ret) {
rtw_hw_scan_abort(rtwdev);
rtw_err(rtwdev, "HW scan failed with status: %d\n", ret);
}
- mutex_unlock(&rtwdev->mutex);
return ret;
}
@@ -973,6 +1001,7 @@ const struct ieee80211_ops rtw_ops = {
.sta_add = rtw_ops_sta_add,
.sta_remove = rtw_ops_sta_remove,
.set_tim = rtw_ops_set_tim,
+ .channel_switch_beacon = rtw_ops_channel_switch_beacon,
.set_key = rtw_ops_set_key,
.ampdu_action = rtw_ops_ampdu_action,
.can_aggregate_in_amsdu = rtw_ops_can_aggregate_in_amsdu,
diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index 0f23498b5c96..48e8cad221b9 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -1550,11 +1550,13 @@ void rtw_core_stop(struct rtw_dev *rtwdev)
clear_bit(RTW_FLAG_RUNNING, rtwdev->flags);
clear_bit(RTW_FLAG_FW_RUNNING, rtwdev->flags);
+ rtwdev->csa_vif = NULL;
mutex_unlock(&rtwdev->mutex);
cancel_work_sync(&rtwdev->c2h_work);
cancel_work_sync(&rtwdev->update_beacon_work);
+ cancel_delayed_work_sync(&rtwdev->csa_beacon_work);
cancel_delayed_work_sync(&rtwdev->watch_dog_work);
cancel_delayed_work_sync(&coex->bt_relink_work);
cancel_delayed_work_sync(&coex->bt_reenable_work);
@@ -2170,6 +2172,7 @@ int rtw_core_init(struct rtw_dev *rtwdev)
INIT_WORK(&rtwdev->ips_work, rtw_ips_work);
INIT_WORK(&rtwdev->fw_recovery_work, rtw_fw_recovery_work);
INIT_WORK(&rtwdev->update_beacon_work, rtw_fw_update_beacon_work);
+ INIT_DELAYED_WORK(&rtwdev->csa_beacon_work, rtw_fw_csa_beacon_work);
INIT_WORK(&rtwdev->ba_work, rtw_txq_ba_work);
skb_queue_head_init(&rtwdev->c2h_queue);
skb_queue_head_init(&rtwdev->coex.queue);
@@ -2293,7 +2296,8 @@ int rtw_register_hw(struct rtw_dev *rtwdev, struct ieee80211_hw *hw)
hw->wiphy->available_antennas_rx = hal->antenna_rx;
hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_TDLS |
- WIPHY_FLAG_TDLS_EXTERNAL_SETUP;
+ WIPHY_FLAG_TDLS_EXTERNAL_SETUP |
+ WIPHY_FLAG_HAS_CHANNEL_SWITCH;
hw->wiphy->features |= NL80211_FEATURE_SCAN_RANDOM_MAC_ADDR;
hw->wiphy->max_scan_ssids = RTW_SCAN_MAX_SSIDS;
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index d59f6e323adf..bc3ebfec11ae 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -2094,6 +2094,9 @@ struct rtw_dev {
struct work_struct ips_work;
struct work_struct fw_recovery_work;
struct work_struct update_beacon_work;
+ struct delayed_work csa_beacon_work;
+ struct ieee80211_vif *csa_vif;
+ ktime_t csa_due;
/* used to protect txqs list */
spinlock_t txq_lock;
--
2.55.0
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH rtw-next v7 3/3] wifi: rtw88: time the countdown downloads from the TBTT
2026-10-20 20:47 [PATCH rtw-next v7 0/3] wifi: rtw88: channel switch in AP mode Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 1/3] wifi: rtw88: download the beacon the reserved page was built with Mehmet Fide
2026-10-20 20:47 ` [PATCH rtw-next v7 2/3] wifi: rtw88: support channel switch in AP mode Mehmet Fide
@ 2026-10-20 20:47 ` Mehmet Fide
2 siblings, 0 replies; 4+ messages in thread
From: Mehmet Fide @ 2026-10-20 20:47 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
The countdown downloads are queued one beacon interval apart, with no
relation to the TBTT. A download that runs late past the next TBTT
leaves a count out of the air.
Queue each download 10 ms after the next TBTT, read from the TSF, so it
may run late by almost a beacon interval; a later one is followed by
the next at once. A TSF jump, an IBSS merge or a reset, restarts the
schedule from the next TBTT.
A TBTT just before the start may already have sent the first count; it
is taken as the one that did, so no count is sent twice.
The USB chips raise no TBTT interrupt, so the TSF register is read. The
beaconing interface is always on port 0: rtw_core_port_switch() moves
an AP there, an IBSS runs alone.
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
Notes:
Changes in v7:
- new patch, from Ping-Ke's review of the countdown pacing in v6
drivers/net/wireless/realtek/rtw88/fw.c | 40 ++++++++++++++++++++---
drivers/net/wireless/realtek/rtw88/main.h | 2 +-
drivers/net/wireless/realtek/rtw88/reg.h | 1 +
3 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 2d81aaeed0d7..c5a106a59540 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -3,6 +3,7 @@
*/
#include <linux/iopoll.h>
+#include <linux/math64.h>
#include "main.h"
#include "coex.h"
@@ -1809,27 +1810,58 @@ bool rtw_fw_csa_active(struct rtw_dev *rtwdev)
return !!rtwdev->csa_vif;
}
-/* paced from the first download: a late one does not delay the next */
+#define RTW_CSA_TBTT_MARGIN_US 10000
+
+/* the beaconing interface is always on port 0 */
+static u64 rtw_fw_read_tsf(struct rtw_dev *rtwdev)
+{
+ u32 hi, lo;
+
+ do {
+ hi = rtw_read32(rtwdev, REG_TSFTR + 4);
+ lo = rtw_read32(rtwdev, REG_TSFTR);
+ } while (hi != rtw_read32(rtwdev, REG_TSFTR + 4));
+
+ return ((u64)hi << 32) | lo;
+}
+
static void rtw_fw_csa_queue(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
{
u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+ u64 tsf = rtw_fw_read_tsf(rtwdev);
s64 delay;
+ u32 rem;
- rtwdev->csa_due = ktime_add_us(rtwdev->csa_due, interval);
- delay = ktime_us_delta(rtwdev->csa_due, ktime_get());
+ rtwdev->csa_tbtt += interval;
+ delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
+ if (delay > interval + RTW_CSA_TBTT_MARGIN_US ||
+ delay < -(s64)interval) {
+ /* the TSF jumped: restart from the next TBTT */
+ div_u64_rem(tsf, interval, &rem);
+ rtwdev->csa_tbtt = tsf - rem + interval;
+ delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
+ }
ieee80211_queue_delayed_work(rtwdev->hw, &rtwdev->csa_beacon_work,
usecs_to_jiffies(max(delay, 0)));
}
void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
{
+ u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+ u32 rem;
+
lockdep_assert_held(&rtwdev->mutex);
if (rtwdev->csa_vif == vif)
return;
rtwdev->csa_vif = vif;
- rtwdev->csa_due = ktime_get();
+ rtwdev->csa_tbtt = rtw_fw_read_tsf(rtwdev);
+ div_u64_rem(rtwdev->csa_tbtt, interval, &rem);
+ rtwdev->csa_tbtt -= rem;
+ /* a TBTT that just passed may have sent the first count already */
+ if (rem < RTW_CSA_TBTT_MARGIN_US)
+ rtwdev->csa_tbtt -= interval;
rtw_fw_csa_queue(rtwdev, vif);
}
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index bc3ebfec11ae..3be0a96d1186 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -2096,7 +2096,7 @@ struct rtw_dev {
struct work_struct update_beacon_work;
struct delayed_work csa_beacon_work;
struct ieee80211_vif *csa_vif;
- ktime_t csa_due;
+ u64 csa_tbtt;
/* used to protect txqs list */
spinlock_t txq_lock;
diff --git a/drivers/net/wireless/realtek/rtw88/reg.h b/drivers/net/wireless/realtek/rtw88/reg.h
index afcdb66fdb9a..3ff4ae0885ef 100644
--- a/drivers/net/wireless/realtek/rtw88/reg.h
+++ b/drivers/net/wireless/realtek/rtw88/reg.h
@@ -506,6 +506,7 @@
#define REG_USTIME_TSF 0x055C
#define REG_BCN_MAX_ERR 0x055D
#define REG_RXTSF_OFFSET_CCK 0x055E
+#define REG_TSFTR 0x0560
#define REG_MISC_CTRL 0x0577
#define BIT_EN_FREE_CNT BIT(3)
#define BIT_DIS_SECOND_CCA (BIT(0) | BIT(1))
--
2.55.0
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