ipq806x: add patch fixing regression from stmmac TX timer

Add patch fixing regression from stmmac TX timer.

Refer to the single patch for extensive details on the problem.

This should restore original performance before 4.19 kernel.

Fixes: #11676
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

target/linux/ipq806x/patches-6.1/700-01-net-introduce-napi_is_scheduled-helper.patch

@@ -0,0 +1,77 @@
+From b5532bdc6d09e6e789417f0c7a0b665b57b0e7be Mon Sep 17 00:00:00 2001
+From: Christian Marangi <ansuelsmth@gmail.com>
+Date: Mon, 18 Sep 2023 14:21:56 +0200
+Subject: [PATCH 1/3] net: introduce napi_is_scheduled helper
+
+We currently have napi_if_scheduled_mark_missed that can be used to
+check if napi is scheduled but that does more thing than simply checking
+it and return a bool. Some driver already implement custom function to
+check if napi is scheduled.
+
+Drop these custom function and introduce napi_is_scheduled that simply
+check if napi is scheduled atomically.
+
+Update any driver and code that implement a similar check and instead
+use this new helper.
+
+Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
+---
+ drivers/net/ethernet/chelsio/cxgb3/sge.c  | 8 --------
+ drivers/net/wireless/realtek/rtw89/core.c | 2 +-
+ include/linux/netdevice.h                 | 5 +++++
+ net/core/dev.c                            | 2 +-
+ 4 files changed, 7 insertions(+), 10 deletions(-)
+
+--- a/drivers/net/ethernet/chelsio/cxgb3/sge.c
++++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c
+@@ -2507,14 +2507,6 @@ static int napi_rx_handler(struct napi_s
+ 	return work_done;
+ }
+ 
+-/*
+- * Returns true if the device is already scheduled for polling.
+- */
+-static inline int napi_is_scheduled(struct napi_struct *napi)
+-{
+-	return test_bit(NAPI_STATE_SCHED, &napi->state);
+-}
+-
+ /**
+  *	process_pure_responses - process pure responses from a response queue
+  *	@adap: the adapter
+--- a/drivers/net/wireless/realtek/rtw89/core.c
++++ b/drivers/net/wireless/realtek/rtw89/core.c
+@@ -1479,7 +1479,7 @@ static void rtw89_core_rx_to_mac80211(st
+ 	struct napi_struct *napi = &rtwdev->napi;
+ 
+ 	/* In low power mode, napi isn't scheduled. Receive it to netif. */
+-	if (unlikely(!test_bit(NAPI_STATE_SCHED, &napi->state)))
++	if (unlikely(!napi_is_scheduled(napi)))
+ 		napi = NULL;
+ 
+ 	rtw89_core_hw_to_sband_rate(rx_status);
+--- a/include/linux/netdevice.h
++++ b/include/linux/netdevice.h
+@@ -468,6 +468,11 @@ static inline bool napi_prefer_busy_poll
+ 	return test_bit(NAPI_STATE_PREFER_BUSY_POLL, &n->state);
+ }
+ 
++static inline bool napi_is_scheduled(struct napi_struct *n)
++{
++	return test_bit(NAPI_STATE_SCHED, &n->state);
++}
++
+ bool napi_schedule_prep(struct napi_struct *n);
+ 
+ /**
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -6562,7 +6562,7 @@ static int __napi_poll(struct napi_struc
+ 	 * accidentally calling ->poll() when NAPI is not scheduled.
+ 	 */
+ 	work = 0;
+-	if (test_bit(NAPI_STATE_SCHED, &n->state)) {
++	if (napi_is_scheduled(n)) {
+ 		work = n->poll(n, weight);
+ 		trace_napi_poll(n, work, weight);
+ 	}

target/linux/ipq806x/patches-6.1/700-02-net-stmmac-improve-TX-timer-arm-logic.patch

@@ -0,0 +1,76 @@
+From 26e872db0f14c09ab57486b538ecc3a24c579df2 Mon Sep 17 00:00:00 2001
+From: Christian Marangi <ansuelsmth@gmail.com>
+Date: Mon, 18 Sep 2023 14:39:01 +0200
+Subject: [PATCH 2/3] net: stmmac: improve TX timer arm logic
+
+There is currently a problem with the TX timer getting armed multiple
+unnecessary times causing big performance regression on some device that
+suffer from heavy handling of hrtimer rearm.
+
+The use of the TX timer is an old implementation that predates the napi
+implementation and the interrupt enable/disable handling.
+
+Due to stmmac being a very old code, the TX timer was never evaluated
+again with this new implementation and was kept there causing
+performance regression. The performance regression started to appear
+with kernel version 4.19 with 8fce33317023 ("net: stmmac: Rework coalesce
+timer and fix multi-queue races") where the timer was reduced to 1ms
+causing it to be armed 40 times more than before.
+
+Decreasing the timer made the problem more present and caused the
+regression in the other of 600-700mbps on some device (regression where
+this was notice is ipq806x).
+
+The problem is in the fact that handling the hrtimer on some target is
+expensive and recent kernel made the timer armed much more times.
+A solution that was proposed was reverting the hrtimer change and use
+mod_timer but such solution would still hide the real problem in the
+current implementation.
+
+To fix the regression, apply some additional logic and skip arming the
+timer when not needed.
+
+Arm the timer ONLY if a napi is not already scheduled. Running the timer
+is redundant since the same function (stmmac_tx_clean) will run in the
+napi TX poll. Also try to cancel any timer if a napi is scheduled to
+prevent redundant run of TX call.
+
+With the following new logic the original performance are restored while
+keeping using the hrtimer.
+
+Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
+---
+ .../net/ethernet/stmicro/stmmac/stmmac_main.c  | 18 +++++++++++++++---
+ 1 file changed, 15 insertions(+), 3 deletions(-)
+
+--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
++++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+@@ -2974,13 +2974,25 @@ static void stmmac_tx_timer_arm(struct s
+ {
+ 	struct stmmac_tx_queue *tx_q = &priv->dma_conf.tx_queue[queue];
+ 	u32 tx_coal_timer = priv->tx_coal_timer[queue];
++	struct stmmac_channel *ch;
++	struct napi_struct *napi;
+ 
+ 	if (!tx_coal_timer)
+ 		return;
+ 
+-	hrtimer_start(&tx_q->txtimer,
+-		      STMMAC_COAL_TIMER(tx_coal_timer),
+-		      HRTIMER_MODE_REL);
++	ch = &priv->channel[tx_q->queue_index];
++	napi = tx_q->xsk_pool ? &ch->rxtx_napi : &ch->tx_napi;
++
++	/* Arm timer only if napi is not already scheduled.
++	 * Try to cancel any timer if napi is scheduled, timer will be armed
++	 * again in the next scheduled napi.
++	 */
++	if (unlikely(!napi_is_scheduled(napi)))
++		hrtimer_start(&tx_q->txtimer,
++			      STMMAC_COAL_TIMER(tx_coal_timer),
++			      HRTIMER_MODE_REL);
++	else
++		hrtimer_try_to_cancel(&tx_q->txtimer);
+ }
+ 
+ /**

target/linux/ipq806x/patches-6.1/700-03-net-stmmac-increase-TX-coalesce-timer-to-5ms.patch

@@ -0,0 +1,37 @@
+From 13e24b0c4318b8b4d0a0fde7e5e7ccb982821c63 Mon Sep 17 00:00:00 2001
+From: Christian Marangi <ansuelsmth@gmail.com>
+Date: Mon, 18 Sep 2023 15:11:13 +0200
+Subject: [PATCH 3/3] net: stmmac: increase TX coalesce timer to 5ms
+
+Commit 8fce33317023 ("net: stmmac: Rework coalesce timer and fix
+multi-queue races") decreased the TX coalesce timer from 40ms to 1ms.
+
+This caused some performance regression on some target (regression was
+reported at least on ipq806x) in the order of 600mbps dropping from
+gigabit handling to only 200mbps.
+
+The problem was identified in the TX timer getting armed too much time.
+While this was fixed and improved in another commit, performance can be
+improved even further by increasing the timer delay a bit moving from
+1ms to 5ms.
+
+The value is a good balance between battery saving by prevending too
+much interrupt to be generated and permitting good performance for
+internet oriented devices.
+
+Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
+---
+ drivers/net/ethernet/stmicro/stmmac/common.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/ethernet/stmicro/stmmac/common.h
++++ b/drivers/net/ethernet/stmicro/stmmac/common.h
+@@ -286,7 +286,7 @@ struct stmmac_safety_stats {
+ #define MIN_DMA_RIWT		0x10
+ #define DEF_DMA_RIWT		0xa0
+ /* Tx coalesce parameters */
+-#define STMMAC_COAL_TX_TIMER	1000
++#define STMMAC_COAL_TX_TIMER	5000
+ #define STMMAC_MAX_COAL_TX_TICK	100000
+ #define STMMAC_TX_MAX_FRAMES	256
+ #define STMMAC_TX_FRAMES	25