* [PATCH rtw-next v2 1/3] wifi: rtw88: usb: bound what the driver feeds the after-DTIM queue
2026-09-07 19:08 [PATCH rtw-next v2 0/3] wifi: rtw88: usb: keep bmc traffic from exhausting the TX page pool Mehmet Fide
@ 2026-09-07 19:08 ` Mehmet Fide
2026-09-10 1:22 ` Ping-Ke Shih
2026-09-07 19:09 ` [PATCH rtw-next v2 2/3] wifi: rtw88: usb: only let the frames a dozing station needs use " Mehmet Fide
2026-09-07 19:09 ` [PATCH rtw-next v2 3/3] wifi: rtw88: widen the ATIM window while an AP interface is up Mehmet Fide
2 siblings, 1 reply; 7+ messages in thread
From: Mehmet Fide @ 2026-09-07 19:08 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
Frames routed to the high queue are transmitted right after DTIM beacons
only, inside the ATIM window, while they wait in the shared TX page pool.
The driver puts no limit on how many it hands over, so as long as one
station dozes, any sustained broadcast or multicast traffic outruns the
drain and empties the pool: measured on an RTL8822BU AP with a single
client in power save and ~40 frames/s of mDNS chatter, the free page
count at 0x240 goes from 1803 to 16 in about 100 seconds and stays there
for as long as the traffic lasts. From that point every other transmit
queues behind the backlog, authentication responses arrive too late for
anyone to join, and the reserved page download fails ("error beacon
valid"). The AP keeps beaconing and only a reboot recovers.
Feed the high queue through a small budget that refills below the
measured drain rate (about 3 frames per DTIM, ~15/s at dtim_period 2 on
the default 2 TU ATIM window); whatever exceeds the budget leaves on its
access category queue right away. The high queue backlog is now bounded
by the burst size under any load, so the page pool cannot run dry, at
the price that a dozing station may miss part of a broadcast storm.
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
v2:
- macro RTW_USB_HIQ_REFILL_INTERVAL for HZ / 10, RTW_USB_HIQ_BUDGET_MAX (Ping-Ke)
- 'budget' instead of 'token': hiq_budget, rtw_usb_hiq_take_budget() (Ping-Ke)
- refill bookkeeping rewritten as elapsed / interval and
hiq_refill = jiffies - elapsed % interval, with a comment (Ping-Ke)
- blank lines after spin_lock_irqsave() and before spin_unlock_irqrestore() (Ping-Ke)
drivers/net/wireless/realtek/rtw88/usb.c | 41 ++++++++++++++++++++++--
drivers/net/wireless/realtek/rtw88/usb.h | 5 +++
2 files changed, 43 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index c90802919473..5482e44f4a88 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -562,7 +562,37 @@ static int rtw_usb_write_data_h2c(struct rtw_dev *rtwdev, u8 *buf, u32 size)
return rtw_usb_write_data(rtwdev, &pkt_info, buf);
}
-static u8 rtw_usb_tx_queue_mapping_to_qsel(struct sk_buff *skb)
+#define RTW_USB_HIQ_REFILL_INTERVAL (HZ / 10) /* jiffies per unit of budget */
+#define RTW_USB_HIQ_BUDGET_MAX 16
+
+static bool rtw_usb_hiq_take_budget(struct rtw_usb *rtwusb)
+{
+ unsigned long flags, elapsed, add;
+ bool ok;
+
+ spin_lock_irqsave(&rtwusb->hiq_lock, flags);
+
+ elapsed = jiffies - rtwusb->hiq_refill;
+ add = elapsed / RTW_USB_HIQ_REFILL_INTERVAL;
+ if (add) {
+ rtwusb->hiq_budget = min_t(unsigned long, rtwusb->hiq_budget + add,
+ RTW_USB_HIQ_BUDGET_MAX);
+ /* The part of the current interval that has not completed yet
+ * keeps counting toward the next unit
+ */
+ rtwusb->hiq_refill = jiffies - elapsed % RTW_USB_HIQ_REFILL_INTERVAL;
+ }
+ ok = rtwusb->hiq_budget > 0;
+ if (ok)
+ rtwusb->hiq_budget--;
+
+ spin_unlock_irqrestore(&rtwusb->hiq_lock, flags);
+
+ return ok;
+}
+
+static u8 rtw_usb_tx_queue_mapping_to_qsel(struct rtw_usb *rtwusb,
+ struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
@@ -573,7 +603,8 @@ static u8 rtw_usb_tx_queue_mapping_to_qsel(struct sk_buff *skb)
qsel = TX_DESC_QSEL_MGMT;
else if (is_broadcast_ether_addr(hdr->addr1) ||
is_multicast_ether_addr(hdr->addr1))
- qsel = (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) ?
+ qsel = (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) &&
+ rtw_usb_hiq_take_budget(rtwusb) ?
TX_DESC_QSEL_HIGH : skb->priority;
else if (skb_get_queue_mapping(skb) <= IEEE80211_AC_BK)
qsel = skb->priority;
@@ -593,7 +624,7 @@ static int rtw_usb_tx_write(struct rtw_dev *rtwdev,
u8 *pkt_desc;
int ep;
- pkt_info->qsel = rtw_usb_tx_queue_mapping_to_qsel(skb);
+ pkt_info->qsel = rtw_usb_tx_queue_mapping_to_qsel(rtwusb, skb);
pkt_desc = skb_push(skb, chip->tx_pkt_desc_sz);
memset(pkt_desc, 0, chip->tx_pkt_desc_sz);
ep = qsel_to_ep(rtwusb, pkt_info->qsel);
@@ -1034,6 +1065,10 @@ static int rtw_usb_init_tx(struct rtw_dev *rtwdev)
struct rtw_usb *rtwusb = rtw_get_usb_priv(rtwdev);
int i;
+ spin_lock_init(&rtwusb->hiq_lock);
+ rtwusb->hiq_budget = RTW_USB_HIQ_BUDGET_MAX;
+ rtwusb->hiq_refill = jiffies;
+
rtwusb->txwq = create_singlethread_workqueue("rtw88_usb: tx wq");
if (!rtwusb->txwq) {
rtw_err(rtwdev, "failed to create TX work queue\n");
diff --git a/drivers/net/wireless/realtek/rtw88/usb.h b/drivers/net/wireless/realtek/rtw88/usb.h
index 9b695b688b24..94ff21dd0846 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.h
+++ b/drivers/net/wireless/realtek/rtw88/usb.h
@@ -75,6 +75,11 @@ struct rtw_usb {
u8 out_ep[RTW_USB_EP_MAX];
int qsel_to_ep[TX_DESC_QSEL_MAX];
+ /* protects hiq_budget and hiq_refill */
+ spinlock_t hiq_lock;
+ u32 hiq_budget;
+ unsigned long hiq_refill;
+
struct workqueue_struct *txwq, *rxwq;
struct sk_buff_head tx_queue[RTW_USB_EP_MAX];
--
2.55.0
^ permalink raw reply [flat|nested] 7+ messages in thread* RE: [PATCH rtw-next v2 1/3] wifi: rtw88: usb: bound what the driver feeds the after-DTIM queue
2026-09-07 19:08 ` [PATCH rtw-next v2 1/3] wifi: rtw88: usb: bound what the driver feeds the after-DTIM queue Mehmet Fide
@ 2026-09-10 1:22 ` Ping-Ke Shih
0 siblings, 0 replies; 7+ messages in thread
From: Ping-Ke Shih @ 2026-09-10 1:22 UTC (permalink / raw)
To: Mehmet Fide; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
Mehmet Fide <mehmet.fide@gmail.com> wrote:
> From: Mehmet Fide <mehmet.fide@screeningeagle.com>
>
> Frames routed to the high queue are transmitted right after DTIM beacons
> only, inside the ATIM window, while they wait in the shared TX page pool.
> The driver puts no limit on how many it hands over, so as long as one
> station dozes, any sustained broadcast or multicast traffic outruns the
> drain and empties the pool: measured on an RTL8822BU AP with a single
> client in power save and ~40 frames/s of mDNS chatter, the free page
> count at 0x240 goes from 1803 to 16 in about 100 seconds and stays there
> for as long as the traffic lasts. From that point every other transmit
> queues behind the backlog, authentication responses arrive too late for
> anyone to join, and the reserved page download fails ("error beacon
> valid"). The AP keeps beaconing and only a reboot recovers.
>
> Feed the high queue through a small budget that refills below the
> measured drain rate (about 3 frames per DTIM, ~15/s at dtim_period 2 on
> the default 2 TU ATIM window); whatever exceeds the budget leaves on its
> access category queue right away. The high queue backlog is now bounded
> by the burst size under any load, so the page pool cannot run dry, at
> the price that a dozing station may miss part of a broadcast storm.
>
> Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
Some minor/nit questions. If you don't change others, just take my
acked-by to v3.
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
>
> drivers/net/wireless/realtek/rtw88/usb.c | 41 ++++++++++++++++++++++--
> drivers/net/wireless/realtek/rtw88/usb.h | 5 +++
> 2 files changed, 43 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
> index c90802919473..5482e44f4a88 100644
> --- a/drivers/net/wireless/realtek/rtw88/usb.c
> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
> @@ -562,7 +562,37 @@ static int rtw_usb_write_data_h2c(struct rtw_dev *rtwdev, u8 *buf, u32 size)
> return rtw_usb_write_data(rtwdev, &pkt_info, buf);
> }
>
> -static u8 rtw_usb_tx_queue_mapping_to_qsel(struct sk_buff *skb)
> +#define RTW_USB_HIQ_REFILL_INTERVAL (HZ / 10) /* jiffies per unit of budget */
Does it mean a budget per 100ms roughly?
> +#define RTW_USB_HIQ_BUDGET_MAX 16
> +
> +static bool rtw_usb_hiq_take_budget(struct rtw_usb *rtwusb)
> +{
> + unsigned long flags, elapsed, add;
> + bool ok;
> +
> + spin_lock_irqsave(&rtwusb->hiq_lock, flags);
> +
> + elapsed = jiffies - rtwusb->hiq_refill;
> + add = elapsed / RTW_USB_HIQ_REFILL_INTERVAL;
> + if (add) {
> + rtwusb->hiq_budget = min_t(unsigned long, rtwusb->hiq_budget + add,
> + RTW_USB_HIQ_BUDGET_MAX);
> + /* The part of the current interval that has not completed yet
> + * keeps counting toward the next unit
> + */
First line of comment block should be empty.
> + rtwusb->hiq_refill = jiffies - elapsed % RTW_USB_HIQ_REFILL_INTERVAL;
> + }
nit: an empty line
> + ok = rtwusb->hiq_budget > 0;
> + if (ok)
> + rtwusb->hiq_budget--;
> +
> + spin_unlock_irqrestore(&rtwusb->hiq_lock, flags);
> +
> + return ok;
> +}
> +
> +static u8 rtw_usb_tx_queue_mapping_to_qsel(struct rtw_usb *rtwusb,
> + struct sk_buff *skb)
> {
> struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
> struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH rtw-next v2 2/3] wifi: rtw88: usb: only let the frames a dozing station needs use the after-DTIM queue
2026-09-07 19:08 [PATCH rtw-next v2 0/3] wifi: rtw88: usb: keep bmc traffic from exhausting the TX page pool Mehmet Fide
2026-09-07 19:08 ` [PATCH rtw-next v2 1/3] wifi: rtw88: usb: bound what the driver feeds the after-DTIM queue Mehmet Fide
@ 2026-09-07 19:09 ` Mehmet Fide
2026-09-10 1:25 ` Ping-Ke Shih
2026-09-07 19:09 ` [PATCH rtw-next v2 3/3] wifi: rtw88: widen the ATIM window while an AP interface is up Mehmet Fide
2 siblings, 1 reply; 7+ messages in thread
From: Mehmet Fide @ 2026-09-07 19:09 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
With the budget in place the high queue can no longer take the chip
down, but ordinary chatter still competes with the frames a sleeping
station actually needs. mac80211 marks every broadcast and multicast
frame with IEEE80211_TX_CTL_SEND_AFTER_DTIM while a station dozes,
mDNS and SSDP included, so under normal traffic the budget is spent on
frames nobody waits for.
Do what the vendor driver does with its default "allow special" high
queue filter: admit only ARP, EAPOL and DHCP to the after-DTIM path,
the frames a station coming out of power save has to see; everything
else goes out on its access category queue at line rate. The frames
are classified the way rtw89_core_tx_btc_spec_pkt_notify() does it,
from skb->protocol and the network and transport header offsets that
mac80211 keeps from the netdev path; EAPOL is the control port flag.
Frames the AP relays between its own stations arrive as ETH_P_802_3
and are not inspected, they leave on the access category queue.
With the filter in place the page pool stays at 1803 through the same
180 second storm, a DHCP flood still takes the after-DTIM path (and is
then held by the budget), and join/ping cycling without power save is
unchanged (10/10).
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
v2:
- classify from skb->protocol, ip_hdr() and udp_hdr() like
rtw89_core_tx_btc_spec_pkt_notify(), EAPOL from the control port flag;
the SNAP/IV parser and linux/unaligned.h are gone (Ping-Ke)
- <linux/*> includes in alphabetical order (Ping-Ke)
- relayed (ETH_P_802_3) frames documented as not inspected
drivers/net/wireless/realtek/rtw88/usb.c | 26 ++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index 5482e44f4a88..473b63d16658 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -2,9 +2,11 @@
/* Copyright(c) 2018-2019 Realtek Corporation
*/
+#include <linux/ip.h>
#include <linux/module.h>
-#include <linux/usb.h>
#include <linux/mutex.h>
+#include <linux/udp.h>
+#include <linux/usb.h>
#include "main.h"
#include "debug.h"
#include "mac.h"
@@ -562,6 +564,26 @@ static int rtw_usb_write_data_h2c(struct rtw_dev *rtwdev, u8 *buf, u32 size)
return rtw_usb_write_data(rtwdev, &pkt_info, buf);
}
+static bool rtw_usb_bmc_needs_dtim(struct sk_buff *skb)
+{
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct udphdr *udphdr;
+
+ if (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO)
+ return true;
+
+ if (skb->protocol == htons(ETH_P_ARP))
+ return true;
+
+ if (skb->protocol != htons(ETH_P_IP) ||
+ ip_hdr(skb)->protocol != IPPROTO_UDP)
+ return false;
+
+ udphdr = udp_hdr(skb);
+
+ return udphdr->dest == htons(67) || udphdr->dest == htons(68);
+}
+
#define RTW_USB_HIQ_REFILL_INTERVAL (HZ / 10) /* jiffies per unit of budget */
#define RTW_USB_HIQ_BUDGET_MAX 16
@@ -604,7 +626,7 @@ static u8 rtw_usb_tx_queue_mapping_to_qsel(struct rtw_usb *rtwusb,
else if (is_broadcast_ether_addr(hdr->addr1) ||
is_multicast_ether_addr(hdr->addr1))
qsel = (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) &&
- rtw_usb_hiq_take_budget(rtwusb) ?
+ rtw_usb_bmc_needs_dtim(skb) && rtw_usb_hiq_take_budget(rtwusb) ?
TX_DESC_QSEL_HIGH : skb->priority;
else if (skb_get_queue_mapping(skb) <= IEEE80211_AC_BK)
qsel = skb->priority;
--
2.55.0
^ permalink raw reply [flat|nested] 7+ messages in thread* RE: [PATCH rtw-next v2 2/3] wifi: rtw88: usb: only let the frames a dozing station needs use the after-DTIM queue
2026-09-07 19:09 ` [PATCH rtw-next v2 2/3] wifi: rtw88: usb: only let the frames a dozing station needs use " Mehmet Fide
@ 2026-09-10 1:25 ` Ping-Ke Shih
0 siblings, 0 replies; 7+ messages in thread
From: Ping-Ke Shih @ 2026-09-10 1:25 UTC (permalink / raw)
To: Mehmet Fide; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
Mehmet Fide <mehmet.fide@gmail.com> wrote:
> +static bool rtw_usb_bmc_needs_dtim(struct sk_buff *skb)
> +{
> + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
> + struct udphdr *udphdr;
> +
> + if (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO)
> + return true;
> +
> + if (skb->protocol == htons(ETH_P_ARP))
> + return true;
> +
> + if (skb->protocol != htons(ETH_P_IP) ||
> + ip_hdr(skb)->protocol != IPPROTO_UDP)
Prefer to list them in positive way.
if (skb->protocol == htons(ETH_P_IP) &&
ip_hdr(skb)->protocol == IPPROTO_UDP) {
udphdr = udp_hdr(skb);
return udphdr->dest == htons(67) || udphdr->dest == htons(68);
}
return false;
> + return false;
> +
> + udphdr = udp_hdr(skb);
> +
> + return udphdr->dest == htons(67) || udphdr->dest == htons(68);
> +}
> +
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH rtw-next v2 3/3] wifi: rtw88: widen the ATIM window while an AP interface is up
2026-09-07 19:08 [PATCH rtw-next v2 0/3] wifi: rtw88: usb: keep bmc traffic from exhausting the TX page pool Mehmet Fide
2026-09-07 19:08 ` [PATCH rtw-next v2 1/3] wifi: rtw88: usb: bound what the driver feeds the after-DTIM queue Mehmet Fide
2026-09-07 19:09 ` [PATCH rtw-next v2 2/3] wifi: rtw88: usb: only let the frames a dozing station needs use " Mehmet Fide
@ 2026-09-07 19:09 ` Mehmet Fide
2026-09-10 1:33 ` Ping-Ke Shih
2 siblings, 1 reply; 7+ messages in thread
From: Mehmet Fide @ 2026-09-07 19:09 UTC (permalink / raw)
To: Ping-Ke Shih; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
From: Mehmet Fide <mehmet.fide@screeningeagle.com>
The frames held for dozing stations go out right after the DTIM beacon
and only for the duration of the ATIM window. The chips come up with a
2 TU window (the two that program it set 0x2 at init), which drains
about three frames per DTIM; the vendor driver sets 0xa or 0xc in AP
mode instead. With the 2 TU window the measured page pool exhaustion
takes ~100 s of ordinary multicast chatter; at 0x4 the same storm
already drains, so 0xa leaves comfortable headroom.
Program 0xa when an AP interface starts and put the default back when
it stops, since most chips never initialize the register themselves.
The bound and the filter of the previous patches still apply: the
window adds drain capacity, the budget protects the pool when that is
not enough, the filter keeps chatter off the beacon-paced path.
Suggested-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---
v2:
- new patch, REG_ATIMWND 0xa in AP mode as in the vendor driver, back to
the 0x2 default on stop_ap since most chips never program it (Ping-Ke)
drivers/net/wireless/realtek/rtw88/mac80211.c | 2 ++
drivers/net/wireless/realtek/rtw88/reg.h | 2 ++
2 files changed, 4 insertions(+)
diff --git a/drivers/net/wireless/realtek/rtw88/mac80211.c b/drivers/net/wireless/realtek/rtw88/mac80211.c
index 0b622d7663b6..2a9b09fa76e7 100644
--- a/drivers/net/wireless/realtek/rtw88/mac80211.c
+++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
@@ -474,6 +474,7 @@ static int rtw_ops_start_ap(struct ieee80211_hw *hw,
mutex_lock(&rtwdev->mutex);
rtw_write32_set(rtwdev, REG_TCR, BIT_TCR_UPDATE_HGQMD);
+ rtw_write16(rtwdev, REG_ATIMWND, ATIMWND_AP);
rtwdev->ap_active = true;
rtw_store_op_chan(rtwdev, true);
chip->ops->phy_calibration(rtwdev);
@@ -490,6 +491,7 @@ static void rtw_ops_stop_ap(struct ieee80211_hw *hw,
mutex_lock(&rtwdev->mutex);
rtw_write32_clr(rtwdev, REG_TCR, BIT_TCR_UPDATE_HGQMD);
+ rtw_write16(rtwdev, REG_ATIMWND, ATIMWND_DEFAULT);
rtwdev->ap_active = false;
if (!rtw_core_check_sta_active(rtwdev))
rtw_clear_op_chan(rtwdev);
diff --git a/drivers/net/wireless/realtek/rtw88/reg.h b/drivers/net/wireless/realtek/rtw88/reg.h
index 08e9494977e0..0b9ba6f37680 100644
--- a/drivers/net/wireless/realtek/rtw88/reg.h
+++ b/drivers/net/wireless/realtek/rtw88/reg.h
@@ -483,6 +483,8 @@
#define REG_DRVERLYINT 0x0558
#define REG_BCNDMATIM 0x0559
#define REG_ATIMWND 0x055A
+#define ATIMWND_DEFAULT 0x2
+#define ATIMWND_AP 0xa
#define REG_USTIME_TSF 0x055C
#define REG_BCN_MAX_ERR 0x055D
#define REG_RXTSF_OFFSET_CCK 0x055E
--
2.55.0
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH rtw-next v2 3/3] wifi: rtw88: widen the ATIM window while an AP interface is up
2026-09-07 19:09 ` [PATCH rtw-next v2 3/3] wifi: rtw88: widen the ATIM window while an AP interface is up Mehmet Fide
@ 2026-09-10 1:33 ` Ping-Ke Shih
0 siblings, 0 replies; 7+ messages in thread
From: Ping-Ke Shih @ 2026-09-10 1:33 UTC (permalink / raw)
To: Mehmet Fide; +Cc: Bitterblue Smith, linux-wireless, linux-kernel, mehmet.fide
Mehmet Fide <mehmet.fide@gmail.com> wrote:
> From: Mehmet Fide <mehmet.fide@screeningeagle.com>
>
> The frames held for dozing stations go out right after the DTIM beacon
> and only for the duration of the ATIM window. The chips come up with a
> 2 TU window (the two that program it set 0x2 at init), which drains
> about three frames per DTIM; the vendor driver sets 0xa or 0xc in AP
> mode instead. With the 2 TU window the measured page pool exhaustion
> takes ~100 s of ordinary multicast chatter; at 0x4 the same storm
> already drains, so 0xa leaves comfortable headroom.
>
> Program 0xa when an AP interface starts and put the default back when
> it stops, since most chips never initialize the register themselves.
> The bound and the filter of the previous patches still apply: the
> window adds drain capacity, the budget protects the pool when that is
> not enough, the filter keeps chatter off the beacon-paced path.
>
> Suggested-by: Ping-Ke Shih <pkshih@realtek.com>
> Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
^ permalink raw reply [flat|nested] 7+ messages in thread