[PATCH v5 00/12] can: m_can: Optimizations for m_can/tcan part 2

[PATCH v5 00/12] can: m_can: Optimizations for m_can/tcan part 2

[Markus Schneider-Pargmann]

Hi Marc, Simon and everyone,

v5 got a rebase on v6.5 with some small style fixes as pointed out in v4.

It is tested on tcan455x but I don't have hardware with mcan on the SoC
myself so any testing is appreciated.

The series implements many small and bigger throughput improvements and
adds rx/tx coalescing at the end.

Based on v6.5-rc1. Also available at
https://gitlab.baylibre.com/msp8/linux/-/tree/topic/mcan-optimization/v6.5?ref_type=heads

Best,
Markus

Changes in v5:
- Add back parenthesis in m_can_set_coalesce(). This will make
  checkpatch unhappy but gcc happy.
- Remove unused fifo_header variable in m_can_tx_handler().
- Rebased to v6.5-rc1

Changes in v4:
- Create and use struct m_can_fifo_element in m_can_tx_handler
- Fix memcpy_and_pad to copy the full buffer
- Fixed a few checkpatch warnings
- Change putidx to be unsigned
- Print hard_xmit error only once when TX FIFO is full

Changes in v3:
- Remove parenthesis in error messages
- Use memcpy_and_pad for buffer copy in 'can: m_can: Write transmit
  header and data in one transaction'.
- Replace spin_lock with spin_lock_irqsave. I got a report of a
  interrupt that was calling start_xmit just after the netqueue was
  woken up before the locked region was exited. spin_lock_irqsave should
  fix this. I attached the full stack at the end of the mail if someone
  wants to know.
- Rebased to v6.3-rc1.
- Removed tcan4x5x patches from this series.

Changes in v2:
- Rebased on v6.2-rc5
- Fixed missing/broken accounting for non peripheral m_can devices.

previous versions:
v1 - https://lore.kernel.org/lkml/20221221152537.751564-1-msp@baylibre.com
v2 - https://lore.kernel.org/lkml/20230125195059.630377-1-msp@baylibre.com
v3 - https://lore.kernel.org/lkml/20230315110546.2518305-1-msp@baylibre.com/
v4 - https://lore.kernel.org/lkml/20230621092350.3130866-1-msp@baylibre.com/

Markus Schneider-Pargmann (12):
  can: m_can: Write transmit header and data in one transaction
  can: m_can: Implement receive coalescing
  can: m_can: Implement transmit coalescing
  can: m_can: Add rx coalescing ethtool support
  can: m_can: Add tx coalescing ethtool support
  can: m_can: Use u32 for putidx
  can: m_can: Cache tx putidx
  can: m_can: Use the workqueue as queue
  can: m_can: Introduce a tx_fifo_in_flight counter
  can: m_can: Use tx_fifo_in_flight for netif_queue control
  can: m_can: Implement BQL
  can: m_can: Implement transmit submission coalescing

 drivers/net/can/m_can/m_can.c | 517 +++++++++++++++++++++++++---------
 drivers/net/can/m_can/m_can.h |  35 ++-
 2 files changed, 418 insertions(+), 134 deletions(-)


base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
-- 
2.40.1

[PATCH v5 01/12] can: m_can: Write transmit header and data in one transaction

[Markus Schneider-Pargmann]

Combine header and data before writing to the transmit fifo to reduce
the overhead for peripheral chips.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/net/can/m_can/m_can.c | 35 +++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index c5af92bcc9c9..478e0670f0d1 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -317,6 +317,12 @@ struct id_and_dlc {
 	u32 dlc;
 };
 
+struct m_can_fifo_element {
+	u32 id;
+	u32 dlc;
+	u8 data[CANFD_MAX_DLEN];
+};
+
 static inline u32 m_can_read(struct m_can_classdev *cdev, enum m_can_reg reg)
 {
 	return cdev->ops->read_reg(cdev, reg);
@@ -1622,9 +1628,10 @@ static int m_can_next_echo_skb_occupied(struct net_device *dev, int putidx)
 static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 {
 	struct canfd_frame *cf = (struct canfd_frame *)cdev->tx_skb->data;
+	u8 len_padded = DIV_ROUND_UP(cf->len, 4);
+	struct m_can_fifo_element fifo_element;
 	struct net_device *dev = cdev->net;
 	struct sk_buff *skb = cdev->tx_skb;
-	struct id_and_dlc fifo_header;
 	u32 cccr, fdflags;
 	u32 txfqs;
 	int err;
@@ -1635,27 +1642,27 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 	/* Generate ID field for TX buffer Element */
 	/* Common to all supported M_CAN versions */
 	if (cf->can_id & CAN_EFF_FLAG) {
-		fifo_header.id = cf->can_id & CAN_EFF_MASK;
-		fifo_header.id |= TX_BUF_XTD;
+		fifo_element.id = cf->can_id & CAN_EFF_MASK;
+		fifo_element.id |= TX_BUF_XTD;
 	} else {
-		fifo_header.id = ((cf->can_id & CAN_SFF_MASK) << 18);
+		fifo_element.id = ((cf->can_id & CAN_SFF_MASK) << 18);
 	}
 
 	if (cf->can_id & CAN_RTR_FLAG)
-		fifo_header.id |= TX_BUF_RTR;
+		fifo_element.id |= TX_BUF_RTR;
 
 	if (cdev->version == 30) {
 		netif_stop_queue(dev);
 
-		fifo_header.dlc = can_fd_len2dlc(cf->len) << 16;
+		fifo_element.dlc = can_fd_len2dlc(cf->len) << 16;
 
 		/* Write the frame ID, DLC, and payload to the FIFO element. */
-		err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &fifo_header, 2);
+		err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &fifo_element, 2);
 		if (err)
 			goto out_fail;
 
 		err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA,
-				       cf->data, DIV_ROUND_UP(cf->len, 4));
+				       cf->data, len_padded);
 		if (err)
 			goto out_fail;
 
@@ -1717,15 +1724,15 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 				fdflags |= TX_BUF_BRS;
 		}
 
-		fifo_header.dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) |
+		fifo_element.dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) |
 			FIELD_PREP(TX_BUF_DLC_MASK, can_fd_len2dlc(cf->len)) |
 			fdflags | TX_BUF_EFC;
-		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &fifo_header, 2);
-		if (err)
-			goto out_fail;
 
-		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA,
-				       cf->data, DIV_ROUND_UP(cf->len, 4));
+		memcpy_and_pad(fifo_element.data, CANFD_MAX_DLEN, &cf->data,
+			       cf->len, 0);
+
+		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID,
+				       &fifo_element, 2 + len_padded);
 		if (err)
 			goto out_fail;
 
-- 
2.40.1

Re: [PATCH v5 01/12] can: m_can: Write transmit header and data in one transaction

[Simon Horman]

On Tue, Jul 18, 2023 at 09:56:57AM +0200, Markus Schneider-Pargmann wrote:
> Combine header and data before writing to the transmit fifo to reduce
> the overhead for peripheral chips.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

[PATCH v5 02/12] can: m_can: Implement receive coalescing

[Markus Schneider-Pargmann]

m_can offers the possibility to set an interrupt on reaching a watermark
level in the receive FIFO. This can be used to implement coalescing.
Unfortunately there is no hardware timeout available to trigger an
interrupt if only a few messages were received within a given time. To
solve this I am using a hrtimer to wake up the irq thread after x
microseconds.

The timer is always started if receive coalescing is enabled and new
received frames were available during an interrupt. The timer is stopped
if during a interrupt handling no new data was available.

If the timer is started the new item interrupt is disabled and the
watermark interrupt takes over. If the timer is not started again, the
new item interrupt is enabled again, notifying the handler about every
new item received.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 70 ++++++++++++++++++++++++++++++++---
 drivers/net/can/m_can/m_can.h |  7 ++++
 2 files changed, 71 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 478e0670f0d1..dd0fa58660d7 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -419,6 +419,22 @@ static void m_can_config_endisable(struct m_can_classdev *cdev, bool enable)
 	}
 }
 
+static void m_can_interrupt_enable(struct m_can_classdev *cdev, u32 interrupts)
+{
+	if (cdev->active_interrupts == interrupts)
+		return;
+	cdev->ops->write_reg(cdev, M_CAN_IE, interrupts);
+	cdev->active_interrupts = interrupts;
+}
+
+static void m_can_coalescing_disable(struct m_can_classdev *cdev)
+{
+	u32 new_interrupts = cdev->active_interrupts | IR_RF0N;
+
+	hrtimer_cancel(&cdev->irq_timer);
+	m_can_interrupt_enable(cdev, new_interrupts);
+}
+
 static inline void m_can_enable_all_interrupts(struct m_can_classdev *cdev)
 {
 	/* Only interrupt line 0 is used in this driver */
@@ -427,6 +443,7 @@ static inline void m_can_enable_all_interrupts(struct m_can_classdev *cdev)
 
 static inline void m_can_disable_all_interrupts(struct m_can_classdev *cdev)
 {
+	m_can_coalescing_disable(cdev);
 	m_can_write(cdev, M_CAN_ILE, 0x0);
 }
 
@@ -1076,15 +1093,39 @@ static int m_can_echo_tx_event(struct net_device *dev)
 	return err;
 }
 
+static void m_can_coalescing_update(struct m_can_classdev *cdev, u32 ir)
+{
+	u32 new_interrupts = cdev->active_interrupts;
+	bool enable_timer = false;
+
+	if (cdev->rx_coalesce_usecs_irq > 0 && (ir & (IR_RF0N | IR_RF0W))) {
+		enable_timer = true;
+		new_interrupts &= ~IR_RF0N;
+	} else if (!hrtimer_active(&cdev->irq_timer)) {
+		new_interrupts |= IR_RF0N;
+	}
+
+	m_can_interrupt_enable(cdev, new_interrupts);
+	if (enable_timer) {
+		hrtimer_start(&cdev->irq_timer,
+			      ns_to_ktime(cdev->rx_coalesce_usecs_irq * NSEC_PER_USEC),
+			      HRTIMER_MODE_REL);
+	}
+}
+
 static irqreturn_t m_can_isr(int irq, void *dev_id)
 {
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	u32 ir;
 
-	if (pm_runtime_suspended(cdev->dev))
+	if (pm_runtime_suspended(cdev->dev)) {
+		m_can_coalescing_disable(cdev);
 		return IRQ_NONE;
+	}
+
 	ir = m_can_read(cdev, M_CAN_IR);
+	m_can_coalescing_update(cdev, ir);
 	if (!ir)
 		return IRQ_NONE;
 
@@ -1099,13 +1140,17 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 	 * - state change IRQ
 	 * - bus error IRQ and bus error reporting
 	 */
-	if ((ir & IR_RF0N) || (ir & IR_ERR_ALL_30X)) {
+	if (ir & (IR_RF0N | IR_RF0W | IR_ERR_ALL_30X)) {
 		cdev->irqstatus = ir;
 		if (!cdev->is_peripheral) {
 			m_can_disable_all_interrupts(cdev);
 			napi_schedule(&cdev->napi);
-		} else if (m_can_rx_peripheral(dev, ir) < 0) {
-			goto out_fail;
+		} else {
+			int pkts;
+
+			pkts = m_can_rx_peripheral(dev, ir);
+			if (pkts < 0)
+				goto out_fail;
 		}
 	}
 
@@ -1141,6 +1186,15 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static enum hrtimer_restart m_can_irq_timer(struct hrtimer *timer)
+{
+	struct m_can_classdev *cdev = container_of(timer, struct m_can_classdev, irq_timer);
+
+	irq_wake_thread(cdev->net->irq, cdev->net);
+
+	return HRTIMER_NORESTART;
+}
+
 static const struct can_bittiming_const m_can_bittiming_const_30X = {
 	.name = KBUILD_MODNAME,
 	.tseg1_min = 2,		/* Time segment 1 = prop_seg + phase_seg1 */
@@ -1281,7 +1335,7 @@ static int m_can_chip_config(struct net_device *dev)
 	/* Disable unused interrupts */
 	interrupts &= ~(IR_ARA | IR_ELO | IR_DRX | IR_TEFF | IR_TEFW | IR_TFE |
 			IR_TCF | IR_HPM | IR_RF1F | IR_RF1W | IR_RF1N |
-			IR_RF0F | IR_RF0W);
+			IR_RF0F);
 
 	m_can_config_endisable(cdev, true);
 
@@ -1325,6 +1379,7 @@ static int m_can_chip_config(struct net_device *dev)
 
 	/* rx fifo configuration, blocking mode, fifo size 1 */
 	m_can_write(cdev, M_CAN_RXF0C,
+		    FIELD_PREP(RXFC_FWM_MASK, cdev->rx_max_coalesced_frames_irq) |
 		    FIELD_PREP(RXFC_FS_MASK, cdev->mcfg[MRAM_RXF0].num) |
 		    cdev->mcfg[MRAM_RXF0].off);
 
@@ -1383,7 +1438,7 @@ static int m_can_chip_config(struct net_device *dev)
 		else
 			interrupts &= ~(IR_ERR_LEC_31X);
 	}
-	m_can_write(cdev, M_CAN_IE, interrupts);
+	m_can_interrupt_enable(cdev, interrupts);
 
 	/* route all interrupts to INT0 */
 	m_can_write(cdev, M_CAN_ILS, ILS_ALL_INT0);
@@ -2047,6 +2102,9 @@ int m_can_class_register(struct m_can_classdev *cdev)
 
 	of_can_transceiver(cdev->net);
 
+	hrtimer_init(&cdev->irq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	cdev->irq_timer.function = m_can_irq_timer;
+
 	dev_info(cdev->dev, "%s device registered (irq=%d, version=%d)\n",
 		 KBUILD_MODNAME, cdev->net->irq, cdev->version);
 
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index a839dc71dc9b..c59099d3f5b9 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -84,6 +84,8 @@ struct m_can_classdev {
 	struct sk_buff *tx_skb;
 	struct phy *transceiver;
 
+	struct hrtimer irq_timer;
+
 	struct m_can_ops *ops;
 
 	int version;
@@ -92,6 +94,11 @@ struct m_can_classdev {
 	int pm_clock_support;
 	int is_peripheral;
 
+	// Cached M_CAN_IE register content
+	u32 active_interrupts;
+	u32 rx_max_coalesced_frames_irq;
+	u32 rx_coalesce_usecs_irq;
+
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };
 
-- 
2.40.1

[PATCH v5 03/12] can: m_can: Implement transmit coalescing

[Markus Schneider-Pargmann]

Extend the coalescing implementation for transmits.

In normal mode the chip raises an interrupt for every finished transmit.
This implementation switches to coalescing mode as soon as an interrupt
handled a transmit. For coalescing the watermark level interrupt is used
to interrupt exactly after x frames were sent. It switches back into
normal mode once there was an interrupt with no finished transmit and
the timer being inactive.

The timer is shared with receive coalescing. The time for receive and
transmit coalescing timers have to be the same for that to work. The
benefit is to have only a single running timer.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 33 ++++++++++++++++++++-------------
 drivers/net/can/m_can/m_can.h |  3 +++
 2 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index dd0fa58660d7..e979aeb2ef13 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -255,6 +255,7 @@ enum m_can_reg {
 #define TXESC_TBDS_64B		0x7
 
 /* Tx Event FIFO Configuration (TXEFC) */
+#define TXEFC_EFWM_MASK		GENMASK(29, 24)
 #define TXEFC_EFS_MASK		GENMASK(21, 16)
 
 /* Tx Event FIFO Status (TXEFS) */
@@ -429,7 +430,7 @@ static void m_can_interrupt_enable(struct m_can_classdev *cdev, u32 interrupts)
 
 static void m_can_coalescing_disable(struct m_can_classdev *cdev)
 {
-	u32 new_interrupts = cdev->active_interrupts | IR_RF0N;
+	u32 new_interrupts = cdev->active_interrupts | IR_RF0N | IR_TEFN;
 
 	hrtimer_cancel(&cdev->irq_timer);
 	m_can_interrupt_enable(cdev, new_interrupts);
@@ -1096,21 +1097,26 @@ static int m_can_echo_tx_event(struct net_device *dev)
 static void m_can_coalescing_update(struct m_can_classdev *cdev, u32 ir)
 {
 	u32 new_interrupts = cdev->active_interrupts;
-	bool enable_timer = false;
+	bool enable_rx_timer = false;
+	bool enable_tx_timer = false;
 
 	if (cdev->rx_coalesce_usecs_irq > 0 && (ir & (IR_RF0N | IR_RF0W))) {
-		enable_timer = true;
+		enable_rx_timer = true;
 		new_interrupts &= ~IR_RF0N;
-	} else if (!hrtimer_active(&cdev->irq_timer)) {
-		new_interrupts |= IR_RF0N;
 	}
+	if (cdev->tx_coalesce_usecs_irq > 0 && (ir & (IR_TEFN | IR_TEFW))) {
+		enable_tx_timer = true;
+		new_interrupts &= ~IR_TEFN;
+	}
+	if (!enable_rx_timer && !hrtimer_active(&cdev->irq_timer))
+		new_interrupts |= IR_RF0N;
+	if (!enable_tx_timer && !hrtimer_active(&cdev->irq_timer))
+		new_interrupts |= IR_TEFN;
 
 	m_can_interrupt_enable(cdev, new_interrupts);
-	if (enable_timer) {
-		hrtimer_start(&cdev->irq_timer,
-			      ns_to_ktime(cdev->rx_coalesce_usecs_irq * NSEC_PER_USEC),
+	if (enable_rx_timer | enable_tx_timer)
+		hrtimer_start(&cdev->irq_timer, cdev->irq_timer_wait,
 			      HRTIMER_MODE_REL);
-	}
 }
 
 static irqreturn_t m_can_isr(int irq, void *dev_id)
@@ -1165,7 +1171,7 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 			netif_wake_queue(dev);
 		}
 	} else  {
-		if (ir & IR_TEFN) {
+		if (ir & (IR_TEFN | IR_TEFW)) {
 			/* New TX FIFO Element arrived */
 			if (m_can_echo_tx_event(dev) != 0)
 				goto out_fail;
@@ -1333,9 +1339,8 @@ static int m_can_chip_config(struct net_device *dev)
 	}
 
 	/* Disable unused interrupts */
-	interrupts &= ~(IR_ARA | IR_ELO | IR_DRX | IR_TEFF | IR_TEFW | IR_TFE |
-			IR_TCF | IR_HPM | IR_RF1F | IR_RF1W | IR_RF1N |
-			IR_RF0F);
+	interrupts &= ~(IR_ARA | IR_ELO | IR_DRX | IR_TEFF | IR_TFE | IR_TCF |
+			IR_HPM | IR_RF1F | IR_RF1W | IR_RF1N | IR_RF0F);
 
 	m_can_config_endisable(cdev, true);
 
@@ -1372,6 +1377,8 @@ static int m_can_chip_config(struct net_device *dev)
 	} else {
 		/* Full TX Event FIFO is used */
 		m_can_write(cdev, M_CAN_TXEFC,
+			    FIELD_PREP(TXEFC_EFWM_MASK,
+				       cdev->tx_max_coalesced_frames_irq) |
 			    FIELD_PREP(TXEFC_EFS_MASK,
 				       cdev->mcfg[MRAM_TXE].num) |
 			    cdev->mcfg[MRAM_TXE].off);
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index c59099d3f5b9..d0c21eddb6ec 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -85,6 +85,7 @@ struct m_can_classdev {
 	struct phy *transceiver;
 
 	struct hrtimer irq_timer;
+	ktime_t irq_timer_wait;
 
 	struct m_can_ops *ops;
 
@@ -98,6 +99,8 @@ struct m_can_classdev {
 	u32 active_interrupts;
 	u32 rx_max_coalesced_frames_irq;
 	u32 rx_coalesce_usecs_irq;
+	u32 tx_max_coalesced_frames_irq;
+	u32 tx_coalesce_usecs_irq;
 
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };
-- 
2.40.1

[PATCH v5 04/12] can: m_can: Add rx coalescing ethtool support

[Markus Schneider-Pargmann]

Add the possibility to set coalescing parameters with ethtool.

rx-frames-irq and rx-usecs-irq can only be set and unset together as the
implemented mechanism would not work otherwise. rx-frames-irq can't be
greater than the RX FIFO size.

Also all values can only be changed if the chip is not active.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 46 +++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index e979aeb2ef13..c19fc10a7645 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1943,8 +1943,54 @@ static const struct net_device_ops m_can_netdev_ops = {
 	.ndo_change_mtu = can_change_mtu,
 };
 
+static int m_can_get_coalesce(struct net_device *dev,
+			      struct ethtool_coalesce *ec,
+			      struct kernel_ethtool_coalesce *kec,
+			      struct netlink_ext_ack *ext_ack)
+{
+	struct m_can_classdev *cdev = netdev_priv(dev);
+
+	ec->rx_max_coalesced_frames_irq = cdev->rx_max_coalesced_frames_irq;
+	ec->rx_coalesce_usecs_irq = cdev->rx_coalesce_usecs_irq;
+
+	return 0;
+}
+
+static int m_can_set_coalesce(struct net_device *dev,
+			      struct ethtool_coalesce *ec,
+			      struct kernel_ethtool_coalesce *kec,
+			      struct netlink_ext_ack *ext_ack)
+{
+	struct m_can_classdev *cdev = netdev_priv(dev);
+
+	if (cdev->can.state != CAN_STATE_STOPPED) {
+		netdev_err(dev, "Device is in use, please shut it down first\n");
+		return -EBUSY;
+	}
+
+	if (ec->rx_max_coalesced_frames_irq > cdev->mcfg[MRAM_RXF0].num) {
+		netdev_err(dev, "rx-frames-irq %u greater than the RX FIFO %u\n",
+			   ec->rx_max_coalesced_frames_irq,
+			   cdev->mcfg[MRAM_RXF0].num);
+		return -EINVAL;
+	}
+	if ((ec->rx_max_coalesced_frames_irq == 0) != (ec->rx_coalesce_usecs_irq == 0)) {
+		netdev_err(dev, "rx-frames-irq and rx-usecs-irq can only be set together\n");
+		return -EINVAL;
+	}
+
+	cdev->rx_max_coalesced_frames_irq = ec->rx_max_coalesced_frames_irq;
+	cdev->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
+
+	return 0;
+}
+
 static const struct ethtool_ops m_can_ethtool_ops = {
+	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
+		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ,
 	.get_ts_info = ethtool_op_get_ts_info,
+	.get_coalesce = m_can_get_coalesce,
+	.set_coalesce = m_can_set_coalesce,
 };
 
 static int register_m_can_dev(struct net_device *dev)
-- 
2.40.1

[PATCH v5 05/12] can: m_can: Add tx coalescing ethtool support

[Markus Schneider-Pargmann]

Add TX support to get/set functions for ethtool coalescing.
tx-frames-irq and tx-usecs-irq can only be set/unset together.
tx-frames-irq needs to be less than TXE and TXB.

As rx and tx share the same timer, rx-usecs-irq and tx-usecs-irq can be
enabled/disabled individually but they need to have the same value if
enabled.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 38 ++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index c19fc10a7645..6af5fa8c7eb3 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1952,6 +1952,8 @@ static int m_can_get_coalesce(struct net_device *dev,
 
 	ec->rx_max_coalesced_frames_irq = cdev->rx_max_coalesced_frames_irq;
 	ec->rx_coalesce_usecs_irq = cdev->rx_coalesce_usecs_irq;
+	ec->tx_max_coalesced_frames_irq = cdev->tx_max_coalesced_frames_irq;
+	ec->tx_coalesce_usecs_irq = cdev->tx_coalesce_usecs_irq;
 
 	return 0;
 }
@@ -1978,16 +1980,50 @@ static int m_can_set_coalesce(struct net_device *dev,
 		netdev_err(dev, "rx-frames-irq and rx-usecs-irq can only be set together\n");
 		return -EINVAL;
 	}
+	if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXE].num) {
+		netdev_err(dev, "tx-frames-irq %u greater than the TX event FIFO %u\n",
+			   ec->tx_max_coalesced_frames_irq,
+			   cdev->mcfg[MRAM_TXE].num);
+		return -EINVAL;
+	}
+	if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXB].num) {
+		netdev_err(dev, "tx-frames-irq %u greater than the TX FIFO %u\n",
+			   ec->tx_max_coalesced_frames_irq,
+			   cdev->mcfg[MRAM_TXB].num);
+		return -EINVAL;
+	}
+	if ((ec->tx_max_coalesced_frames_irq == 0) != (ec->tx_coalesce_usecs_irq == 0)) {
+		netdev_err(dev, "tx-frames-irq and tx-usecs-irq can only be set together\n");
+		return -EINVAL;
+	}
+	if (ec->rx_coalesce_usecs_irq != 0 && ec->tx_coalesce_usecs_irq != 0 &&
+	    ec->rx_coalesce_usecs_irq != ec->tx_coalesce_usecs_irq) {
+		netdev_err(dev, "rx-usecs-irq %u needs to be equal to tx-usecs-irq %u if both are enabled\n",
+			   ec->rx_coalesce_usecs_irq,
+			   ec->tx_coalesce_usecs_irq);
+		return -EINVAL;
+	}
 
 	cdev->rx_max_coalesced_frames_irq = ec->rx_max_coalesced_frames_irq;
 	cdev->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
+	cdev->tx_max_coalesced_frames_irq = ec->tx_max_coalesced_frames_irq;
+	cdev->tx_coalesce_usecs_irq = ec->tx_coalesce_usecs_irq;
+
+	if (cdev->rx_coalesce_usecs_irq)
+		cdev->irq_timer_wait =
+			ns_to_ktime(cdev->rx_coalesce_usecs_irq * NSEC_PER_USEC);
+	else
+		cdev->irq_timer_wait =
+			ns_to_ktime(cdev->tx_coalesce_usecs_irq * NSEC_PER_USEC);
 
 	return 0;
 }
 
 static const struct ethtool_ops m_can_ethtool_ops = {
 	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
-		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ,
+		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ |
+		ETHTOOL_COALESCE_TX_USECS_IRQ |
+		ETHTOOL_COALESCE_TX_MAX_FRAMES_IRQ,
 	.get_ts_info = ethtool_op_get_ts_info,
 	.get_coalesce = m_can_get_coalesce,
 	.set_coalesce = m_can_set_coalesce,
-- 
2.40.1

[PATCH v5 06/12] can: m_can: Use u32 for putidx

[Markus Schneider-Pargmann]

putidx is not an integer normally, it is an unsigned field used in
hardware registers. Use a u32 for it.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/net/can/m_can/m_can.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 6af5fa8c7eb3..6a815812ae38 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -467,7 +467,7 @@ static void m_can_clean(struct net_device *net)
 	struct m_can_classdev *cdev = netdev_priv(net);
 
 	if (cdev->tx_skb) {
-		int putidx = 0;
+		u32 putidx = 0;
 
 		net->stats.tx_errors++;
 		if (cdev->version > 30)
@@ -1673,12 +1673,12 @@ static int m_can_close(struct net_device *dev)
 	return 0;
 }
 
-static int m_can_next_echo_skb_occupied(struct net_device *dev, int putidx)
+static int m_can_next_echo_skb_occupied(struct net_device *dev, u32 putidx)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
 	/*get wrap around for loopback skb index */
 	unsigned int wrap = cdev->can.echo_skb_max;
-	int next_idx;
+	u32 next_idx;
 
 	/* calculate next index */
 	next_idx = (++putidx >= wrap ? 0 : putidx);
@@ -1697,7 +1697,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 	u32 cccr, fdflags;
 	u32 txfqs;
 	int err;
-	int putidx;
+	u32 putidx;
 
 	cdev->tx_skb = NULL;
 
-- 
2.40.1

Re: [PATCH v5 06/12] can: m_can: Use u32 for putidx

[Simon Horman]

On Tue, Jul 18, 2023 at 09:57:02AM +0200, Markus Schneider-Pargmann wrote:
> putidx is not an integer normally, it is an unsigned field used in
> hardware registers. Use a u32 for it.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

[PATCH v5 07/12] can: m_can: Cache tx putidx

[Markus Schneider-Pargmann]

m_can_tx_handler is the only place where data is written to the tx fifo.
We can calculate the putidx in the driver code here to avoid the
dependency on the txfqs register.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 8 +++++++-
 drivers/net/can/m_can/m_can.h | 3 +++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 6a815812ae38..45e8afb1b795 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1482,6 +1482,10 @@ static int m_can_start(struct net_device *dev)
 
 	m_can_enable_all_interrupts(cdev);
 
+	if (cdev->version > 30)
+		cdev->tx_fifo_putidx = FIELD_GET(TXFQS_TFQPI_MASK,
+						 m_can_read(cdev, M_CAN_TXFQS));
+
 	return 0;
 }
 
@@ -1771,7 +1775,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 		}
 
 		/* get put index for frame */
-		putidx = FIELD_GET(TXFQS_TFQPI_MASK, txfqs);
+		putidx = cdev->tx_fifo_putidx;
 
 		/* Construct DLC Field, with CAN-FD configuration.
 		 * Use the put index of the fifo as the message marker,
@@ -1805,6 +1809,8 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 
 		/* Enable TX FIFO element to start transfer  */
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
+		cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
+					0 : cdev->tx_fifo_putidx);
 
 		/* stop network queue if fifo full */
 		if (m_can_tx_fifo_full(cdev) ||
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index d0c21eddb6ec..548ae908ac4e 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -102,6 +102,9 @@ struct m_can_classdev {
 	u32 tx_max_coalesced_frames_irq;
 	u32 tx_coalesce_usecs_irq;
 
+	// Store this internally to avoid fetch delays on peripheral chips
+	int tx_fifo_putidx;
+
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };
 
-- 
2.40.1

[PATCH v5 08/12] can: m_can: Use the workqueue as queue

[Markus Schneider-Pargmann]

The current implementation uses the workqueue for peripheral chips to
submit work. Only a single work item is queued and used at any time.

To be able to keep more than one transmit in flight at a time, prepare
the workqueue to support multiple transmits at the same time.

Each work item now has a separate storage for a skb and a pointer to
cdev. This assures that each workitem can be processed individually.

The workqueue is replaced by an ordered workqueue which makes sure that
only a single worker processes the items queued on the workqueue. Also
items are ordered by the order they were enqueued. This removes most of
the concurrency the workqueue normally offers. It is not necessary for
this driver.

The cleanup functions have to be adopted a bit to handle this new
mechanism.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 109 ++++++++++++++++++++--------------
 drivers/net/can/m_can/m_can.h |  14 ++++-
 2 files changed, 75 insertions(+), 48 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 45e8afb1b795..9e4dcdfda59d 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -466,17 +466,16 @@ static void m_can_clean(struct net_device *net)
 {
 	struct m_can_classdev *cdev = netdev_priv(net);
 
-	if (cdev->tx_skb) {
-		u32 putidx = 0;
+	for (int i = 0; i != cdev->tx_fifo_size; ++i) {
+		if (!cdev->tx_ops[i].skb)
+			continue;
 
 		net->stats.tx_errors++;
-		if (cdev->version > 30)
-			putidx = FIELD_GET(TXFQS_TFQPI_MASK,
-					   m_can_read(cdev, M_CAN_TXFQS));
-
-		can_free_echo_skb(cdev->net, putidx, NULL);
-		cdev->tx_skb = NULL;
+		cdev->tx_ops[i].skb = NULL;
 	}
+
+	for (int i = 0; i != cdev->can.echo_skb_max; ++i)
+		can_free_echo_skb(cdev->net, i, NULL);
 }
 
 /* For peripherals, pass skb to rx-offload, which will push skb from
@@ -1663,8 +1662,9 @@ static int m_can_close(struct net_device *dev)
 	m_can_clk_stop(cdev);
 	free_irq(dev->irq, dev);
 
+	m_can_clean(dev);
+
 	if (cdev->is_peripheral) {
-		cdev->tx_skb = NULL;
 		destroy_workqueue(cdev->tx_wq);
 		cdev->tx_wq = NULL;
 		can_rx_offload_disable(&cdev->offload);
@@ -1691,20 +1691,18 @@ static int m_can_next_echo_skb_occupied(struct net_device *dev, u32 putidx)
 	return !!cdev->can.echo_skb[next_idx];
 }
 
-static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
+static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
+				    struct sk_buff *skb)
 {
-	struct canfd_frame *cf = (struct canfd_frame *)cdev->tx_skb->data;
+	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
 	u8 len_padded = DIV_ROUND_UP(cf->len, 4);
 	struct m_can_fifo_element fifo_element;
 	struct net_device *dev = cdev->net;
-	struct sk_buff *skb = cdev->tx_skb;
 	u32 cccr, fdflags;
 	u32 txfqs;
 	int err;
 	u32 putidx;
 
-	cdev->tx_skb = NULL;
-
 	/* Generate ID field for TX buffer Element */
 	/* Common to all supported M_CAN versions */
 	if (cf->can_id & CAN_EFF_FLAG) {
@@ -1828,10 +1826,36 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 
 static void m_can_tx_work_queue(struct work_struct *ws)
 {
-	struct m_can_classdev *cdev = container_of(ws, struct m_can_classdev,
-						   tx_work);
+	struct m_can_tx_op *op = container_of(ws, struct m_can_tx_op, work);
+	struct m_can_classdev *cdev = op->cdev;
+	struct sk_buff *skb = op->skb;
 
-	m_can_tx_handler(cdev);
+	op->skb = NULL;
+	m_can_tx_handler(cdev, skb);
+}
+
+static void m_can_tx_queue_skb(struct m_can_classdev *cdev, struct sk_buff *skb)
+{
+	cdev->tx_ops[cdev->next_tx_op].skb = skb;
+	queue_work(cdev->tx_wq, &cdev->tx_ops[cdev->next_tx_op].work);
+
+	++cdev->next_tx_op;
+	if (cdev->next_tx_op >= cdev->tx_fifo_size)
+		cdev->next_tx_op = 0;
+}
+
+static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
+					       struct sk_buff *skb)
+{
+	if (cdev->can.state == CAN_STATE_BUS_OFF) {
+		m_can_clean(cdev->net);
+		return NETDEV_TX_OK;
+	}
+
+	netif_stop_queue(cdev->net);
+	m_can_tx_queue_skb(cdev, skb);
+
+	return NETDEV_TX_OK;
 }
 
 static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
@@ -1842,30 +1866,10 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
-	if (cdev->is_peripheral) {
-		if (cdev->tx_skb) {
-			netdev_err(dev, "hard_xmit called while tx busy\n");
-			return NETDEV_TX_BUSY;
-		}
-
-		if (cdev->can.state == CAN_STATE_BUS_OFF) {
-			m_can_clean(dev);
-		} else {
-			/* Need to stop the queue to avoid numerous requests
-			 * from being sent.  Suggested improvement is to create
-			 * a queueing mechanism that will queue the skbs and
-			 * process them in order.
-			 */
-			cdev->tx_skb = skb;
-			netif_stop_queue(cdev->net);
-			queue_work(cdev->tx_wq, &cdev->tx_work);
-		}
-	} else {
-		cdev->tx_skb = skb;
-		return m_can_tx_handler(cdev);
-	}
-
-	return NETDEV_TX_OK;
+	if (cdev->is_peripheral)
+		return m_can_start_peripheral_xmit(cdev, skb);
+	else
+		return m_can_tx_handler(cdev, skb);
 }
 
 static int m_can_open(struct net_device *dev)
@@ -1893,15 +1897,17 @@ static int m_can_open(struct net_device *dev)
 
 	/* register interrupt handler */
 	if (cdev->is_peripheral) {
-		cdev->tx_skb = NULL;
-		cdev->tx_wq = alloc_workqueue("mcan_wq",
-					      WQ_FREEZABLE | WQ_MEM_RECLAIM, 0);
+		cdev->tx_wq = alloc_ordered_workqueue("mcan_wq",
+						      WQ_FREEZABLE | WQ_MEM_RECLAIM);
 		if (!cdev->tx_wq) {
 			err = -ENOMEM;
 			goto out_wq_fail;
 		}
 
-		INIT_WORK(&cdev->tx_work, m_can_tx_work_queue);
+		for (int i = 0; i != cdev->tx_fifo_size; ++i) {
+			cdev->tx_ops[i].cdev = cdev;
+			INIT_WORK(&cdev->tx_ops[i].work, m_can_tx_work_queue);
+		}
 
 		err = request_threaded_irq(dev->irq, NULL, m_can_isr,
 					   IRQF_ONESHOT,
@@ -2171,6 +2177,19 @@ int m_can_class_register(struct m_can_classdev *cdev)
 {
 	int ret;
 
+	cdev->tx_fifo_size = max(1, min(cdev->mcfg[MRAM_TXB].num,
+					cdev->mcfg[MRAM_TXE].num));
+	if (cdev->is_peripheral) {
+		cdev->tx_ops =
+			devm_kzalloc(cdev->dev,
+				     cdev->tx_fifo_size * sizeof(*cdev->tx_ops),
+				     GFP_KERNEL);
+		if (!cdev->tx_ops) {
+			dev_err(cdev->dev, "Failed to allocate tx_ops for workqueue\n");
+			return -ENOMEM;
+		}
+	}
+
 	if (cdev->pm_clock_support) {
 		ret = m_can_clk_start(cdev);
 		if (ret)
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index 548ae908ac4e..38b154fea04b 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -70,6 +70,12 @@ struct m_can_ops {
 	int (*init)(struct m_can_classdev *cdev);
 };
 
+struct m_can_tx_op {
+	struct m_can_classdev *cdev;
+	struct work_struct work;
+	struct sk_buff *skb;
+};
+
 struct m_can_classdev {
 	struct can_priv can;
 	struct can_rx_offload offload;
@@ -80,8 +86,6 @@ struct m_can_classdev {
 	struct clk *cclk;
 
 	struct workqueue_struct *tx_wq;
-	struct work_struct tx_work;
-	struct sk_buff *tx_skb;
 	struct phy *transceiver;
 
 	struct hrtimer irq_timer;
@@ -103,7 +107,11 @@ struct m_can_classdev {
 	u32 tx_coalesce_usecs_irq;
 
 	// Store this internally to avoid fetch delays on peripheral chips
-	int tx_fifo_putidx;
+	u32 tx_fifo_putidx;
+
+	struct m_can_tx_op *tx_ops;
+	int tx_fifo_size;
+	int next_tx_op;
 
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };
-- 
2.40.1

[PATCH v5 09/12] can: m_can: Introduce a tx_fifo_in_flight counter

[Markus Schneider-Pargmann]

Keep track of the number of transmits in flight.

This patch prepares the driver to control the network interface queue
based on this counter. By itself this counter be
implemented with an atomic, but as we need to do other things in the
critical sections later I am using a spinlock instead.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 41 ++++++++++++++++++++++++++++++++++-
 drivers/net/can/m_can/m_can.h |  4 ++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 9e4dcdfda59d..98ca5d13916b 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -465,6 +465,7 @@ static u32 m_can_get_timestamp(struct m_can_classdev *cdev)
 static void m_can_clean(struct net_device *net)
 {
 	struct m_can_classdev *cdev = netdev_priv(net);
+	unsigned long irqflags;
 
 	for (int i = 0; i != cdev->tx_fifo_size; ++i) {
 		if (!cdev->tx_ops[i].skb)
@@ -476,6 +477,10 @@ static void m_can_clean(struct net_device *net)
 
 	for (int i = 0; i != cdev->can.echo_skb_max; ++i)
 		can_free_echo_skb(cdev->net, i, NULL);
+
+	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
+	cdev->tx_fifo_in_flight = 0;
+	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
 }
 
 /* For peripherals, pass skb to rx-offload, which will push skb from
@@ -1046,6 +1051,24 @@ static void m_can_tx_update_stats(struct m_can_classdev *cdev,
 	stats->tx_packets++;
 }
 
+static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted)
+{
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
+	cdev->tx_fifo_in_flight -= transmitted;
+	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
+}
+
+static void m_can_start_tx(struct m_can_classdev *cdev)
+{
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
+	++cdev->tx_fifo_in_flight;
+	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
+}
+
 static int m_can_echo_tx_event(struct net_device *dev)
 {
 	u32 txe_count = 0;
@@ -1055,6 +1078,7 @@ static int m_can_echo_tx_event(struct net_device *dev)
 	int i = 0;
 	int err = 0;
 	unsigned int msg_mark;
+	int processed = 0;
 
 	struct m_can_classdev *cdev = netdev_priv(dev);
 
@@ -1084,12 +1108,15 @@ static int m_can_echo_tx_event(struct net_device *dev)
 
 		/* update stats */
 		m_can_tx_update_stats(cdev, msg_mark, timestamp);
+		++processed;
 	}
 
 	if (ack_fgi != -1)
 		m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
 							  ack_fgi));
 
+	m_can_finish_tx(cdev, processed);
+
 	return err;
 }
 
@@ -1168,6 +1195,7 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 				timestamp = m_can_get_timestamp(cdev);
 			m_can_tx_update_stats(cdev, 0, timestamp);
 			netif_wake_queue(dev);
+			m_can_finish_tx(cdev, 1);
 		}
 	} else  {
 		if (ir & (IR_TEFN | IR_TEFW)) {
@@ -1853,11 +1881,22 @@ static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
 	}
 
 	netif_stop_queue(cdev->net);
+
+	m_can_start_tx(cdev);
+
 	m_can_tx_queue_skb(cdev, skb);
 
 	return NETDEV_TX_OK;
 }
 
+static netdev_tx_t m_can_start_fast_xmit(struct m_can_classdev *cdev,
+					 struct sk_buff *skb)
+{
+	m_can_start_tx(cdev);
+
+	return m_can_tx_handler(cdev, skb);
+}
+
 static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 				    struct net_device *dev)
 {
@@ -1869,7 +1908,7 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	if (cdev->is_peripheral)
 		return m_can_start_peripheral_xmit(cdev, skb);
 	else
-		return m_can_tx_handler(cdev, skb);
+		return m_can_start_fast_xmit(cdev, skb);
 }
 
 static int m_can_open(struct net_device *dev)
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index 38b154fea04b..5c182aece15c 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -109,6 +109,10 @@ struct m_can_classdev {
 	// Store this internally to avoid fetch delays on peripheral chips
 	u32 tx_fifo_putidx;
 
+	/* Protects shared state between start_xmit and m_can_isr */
+	spinlock_t tx_handling_spinlock;
+	int tx_fifo_in_flight;
+
 	struct m_can_tx_op *tx_ops;
 	int tx_fifo_size;
 	int next_tx_op;
-- 
2.40.1

[PATCH v5 10/12] can: m_can: Use tx_fifo_in_flight for netif_queue control

[Markus Schneider-Pargmann]

The network queue is currently always stopped in start_xmit and
continued in the interrupt handler. This is not possible anymore if we
want to keep multiple transmits in flight in parallel.

Use the previously introduced tx_fifo_in_flight counter to control the
network queue instead. This has the benefit of not needing to ask the
hardware about fifo status.

This patch stops the network queue in start_xmit if the number of
transmits in flight reaches the size of the fifo and wakes up the queue
from the interrupt handler once the transmits in flight drops below the
fifo size. This means any skbs over the limit will be rejected
immediately in start_xmit (it shouldn't be possible at all to reach that
state anyways).

The maximum number of transmits in flight is the size of the fifo.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/net/can/m_can/m_can.c | 85 +++++++++++------------------------
 1 file changed, 26 insertions(+), 59 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 98ca5d13916b..c01f60317e31 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -376,16 +376,6 @@ m_can_txe_fifo_read(struct m_can_classdev *cdev, u32 fgi, u32 offset, u32 *val)
 	return cdev->ops->read_fifo(cdev, addr_offset, val, 1);
 }
 
-static inline bool _m_can_tx_fifo_full(u32 txfqs)
-{
-	return !!(txfqs & TXFQS_TFQF);
-}
-
-static inline bool m_can_tx_fifo_full(struct m_can_classdev *cdev)
-{
-	return _m_can_tx_fifo_full(m_can_read(cdev, M_CAN_TXFQS));
-}
-
 static void m_can_config_endisable(struct m_can_classdev *cdev, bool enable)
 {
 	u32 cccr = m_can_read(cdev, M_CAN_CCCR);
@@ -1056,17 +1046,31 @@ static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted)
 	unsigned long irqflags;
 
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
+	if (cdev->tx_fifo_in_flight >= cdev->tx_fifo_size && transmitted > 0)
+		netif_wake_queue(cdev->net);
 	cdev->tx_fifo_in_flight -= transmitted;
 	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
 }
 
-static void m_can_start_tx(struct m_can_classdev *cdev)
+static netdev_tx_t m_can_start_tx(struct m_can_classdev *cdev)
 {
 	unsigned long irqflags;
+	int tx_fifo_in_flight;
 
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
-	++cdev->tx_fifo_in_flight;
+	tx_fifo_in_flight = cdev->tx_fifo_in_flight + 1;
+	if (tx_fifo_in_flight >= cdev->tx_fifo_size) {
+		netif_stop_queue(cdev->net);
+		if (tx_fifo_in_flight > cdev->tx_fifo_size) {
+			netdev_err_once(cdev->net, "hard_xmit called while TX FIFO full\n");
+			spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
+			return NETDEV_TX_BUSY;
+		}
+	}
+	cdev->tx_fifo_in_flight = tx_fifo_in_flight;
 	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
+
+	return NETDEV_TX_OK;
 }
 
 static int m_can_echo_tx_event(struct net_device *dev)
@@ -1194,7 +1198,6 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 			if (cdev->is_peripheral)
 				timestamp = m_can_get_timestamp(cdev);
 			m_can_tx_update_stats(cdev, 0, timestamp);
-			netif_wake_queue(dev);
 			m_can_finish_tx(cdev, 1);
 		}
 	} else  {
@@ -1202,10 +1205,6 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 			/* New TX FIFO Element arrived */
 			if (m_can_echo_tx_event(dev) != 0)
 				goto out_fail;
-
-			if (netif_queue_stopped(dev) &&
-			    !m_can_tx_fifo_full(cdev))
-				netif_wake_queue(dev);
 		}
 	}
 
@@ -1705,20 +1704,6 @@ static int m_can_close(struct net_device *dev)
 	return 0;
 }
 
-static int m_can_next_echo_skb_occupied(struct net_device *dev, u32 putidx)
-{
-	struct m_can_classdev *cdev = netdev_priv(dev);
-	/*get wrap around for loopback skb index */
-	unsigned int wrap = cdev->can.echo_skb_max;
-	u32 next_idx;
-
-	/* calculate next index */
-	next_idx = (++putidx >= wrap ? 0 : putidx);
-
-	/* check if occupied */
-	return !!cdev->can.echo_skb[next_idx];
-}
-
 static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 				    struct sk_buff *skb)
 {
@@ -1727,7 +1712,6 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 	struct m_can_fifo_element fifo_element;
 	struct net_device *dev = cdev->net;
 	u32 cccr, fdflags;
-	u32 txfqs;
 	int err;
 	u32 putidx;
 
@@ -1782,24 +1766,6 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 	} else {
 		/* Transmit routine for version >= v3.1.x */
 
-		txfqs = m_can_read(cdev, M_CAN_TXFQS);
-
-		/* Check if FIFO full */
-		if (_m_can_tx_fifo_full(txfqs)) {
-			/* This shouldn't happen */
-			netif_stop_queue(dev);
-			netdev_warn(dev,
-				    "TX queue active although FIFO is full.");
-
-			if (cdev->is_peripheral) {
-				kfree_skb(skb);
-				dev->stats.tx_dropped++;
-				return NETDEV_TX_OK;
-			} else {
-				return NETDEV_TX_BUSY;
-			}
-		}
-
 		/* get put index for frame */
 		putidx = cdev->tx_fifo_putidx;
 
@@ -1837,11 +1803,6 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
 		cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
 					0 : cdev->tx_fifo_putidx);
-
-		/* stop network queue if fifo full */
-		if (m_can_tx_fifo_full(cdev) ||
-		    m_can_next_echo_skb_occupied(dev, putidx))
-			netif_stop_queue(dev);
 	}
 
 	return NETDEV_TX_OK;
@@ -1875,14 +1836,16 @@ static void m_can_tx_queue_skb(struct m_can_classdev *cdev, struct sk_buff *skb)
 static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
 					       struct sk_buff *skb)
 {
+	netdev_tx_t err;
+
 	if (cdev->can.state == CAN_STATE_BUS_OFF) {
 		m_can_clean(cdev->net);
 		return NETDEV_TX_OK;
 	}
 
-	netif_stop_queue(cdev->net);
-
-	m_can_start_tx(cdev);
+	err = m_can_start_tx(cdev);
+	if (err != NETDEV_TX_OK)
+		return err;
 
 	m_can_tx_queue_skb(cdev, skb);
 
@@ -1892,7 +1855,11 @@ static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
 static netdev_tx_t m_can_start_fast_xmit(struct m_can_classdev *cdev,
 					 struct sk_buff *skb)
 {
-	m_can_start_tx(cdev);
+	netdev_tx_t err;
+
+	err = m_can_start_tx(cdev);
+	if (err != NETDEV_TX_OK)
+		return err;
 
 	return m_can_tx_handler(cdev, skb);
 }
-- 
2.40.1

Re: [PATCH v5 10/12] can: m_can: Use tx_fifo_in_flight for netif_queue control

[Simon Horman]

On Tue, Jul 18, 2023 at 09:57:06AM +0200, Markus Schneider-Pargmann wrote:
> The network queue is currently always stopped in start_xmit and
> continued in the interrupt handler. This is not possible anymore if we
> want to keep multiple transmits in flight in parallel.
> 
> Use the previously introduced tx_fifo_in_flight counter to control the
> network queue instead. This has the benefit of not needing to ask the
> hardware about fifo status.
> 
> This patch stops the network queue in start_xmit if the number of
> transmits in flight reaches the size of the fifo and wakes up the queue
> from the interrupt handler once the transmits in flight drops below the
> fifo size. This means any skbs over the limit will be rejected
> immediately in start_xmit (it shouldn't be possible at all to reach that
> state anyways).
> 
> The maximum number of transmits in flight is the size of the fifo.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

[PATCH v5 11/12] can: m_can: Implement BQL

[Markus Schneider-Pargmann]

Implement byte queue limiting in preparation for the use of xmit_more().

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/can/m_can/m_can.c | 49 +++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index c01f60317e31..b775ee8e5ff5 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -468,6 +468,8 @@ static void m_can_clean(struct net_device *net)
 	for (int i = 0; i != cdev->can.echo_skb_max; ++i)
 		can_free_echo_skb(cdev->net, i, NULL);
 
+	netdev_reset_queue(cdev->net);
+
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
 	cdev->tx_fifo_in_flight = 0;
 	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
@@ -1022,29 +1024,34 @@ static int m_can_poll(struct napi_struct *napi, int quota)
  * echo. timestamp is used for peripherals to ensure correct ordering
  * by rx-offload, and is ignored for non-peripherals.
  */
-static void m_can_tx_update_stats(struct m_can_classdev *cdev,
-				  unsigned int msg_mark,
-				  u32 timestamp)
+static unsigned int m_can_tx_update_stats(struct m_can_classdev *cdev,
+					  unsigned int msg_mark, u32 timestamp)
 {
 	struct net_device *dev = cdev->net;
 	struct net_device_stats *stats = &dev->stats;
+	unsigned int frame_len;
 
 	if (cdev->is_peripheral)
 		stats->tx_bytes +=
 			can_rx_offload_get_echo_skb(&cdev->offload,
 						    msg_mark,
 						    timestamp,
-						    NULL);
+						    &frame_len);
 	else
-		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, NULL);
+		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, &frame_len);
 
 	stats->tx_packets++;
+
+	return frame_len;
 }
 
-static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted)
+static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted,
+			    unsigned int transmitted_frame_len)
 {
 	unsigned long irqflags;
 
+	netdev_completed_queue(cdev->net, transmitted, transmitted_frame_len);
+
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
 	if (cdev->tx_fifo_in_flight >= cdev->tx_fifo_size && transmitted > 0)
 		netif_wake_queue(cdev->net);
@@ -1083,6 +1090,7 @@ static int m_can_echo_tx_event(struct net_device *dev)
 	int err = 0;
 	unsigned int msg_mark;
 	int processed = 0;
+	unsigned int processed_frame_len = 0;
 
 	struct m_can_classdev *cdev = netdev_priv(dev);
 
@@ -1111,7 +1119,9 @@ static int m_can_echo_tx_event(struct net_device *dev)
 		fgi = (++fgi >= cdev->mcfg[MRAM_TXE].num ? 0 : fgi);
 
 		/* update stats */
-		m_can_tx_update_stats(cdev, msg_mark, timestamp);
+		processed_frame_len += m_can_tx_update_stats(cdev, msg_mark,
+							     timestamp);
+
 		++processed;
 	}
 
@@ -1119,7 +1129,7 @@ static int m_can_echo_tx_event(struct net_device *dev)
 		m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
 							  ack_fgi));
 
-	m_can_finish_tx(cdev, processed);
+	m_can_finish_tx(cdev, processed, processed_frame_len);
 
 	return err;
 }
@@ -1194,11 +1204,12 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 		if (ir & IR_TC) {
 			/* Transmission Complete Interrupt*/
 			u32 timestamp = 0;
+			unsigned int frame_len;
 
 			if (cdev->is_peripheral)
 				timestamp = m_can_get_timestamp(cdev);
-			m_can_tx_update_stats(cdev, 0, timestamp);
-			m_can_finish_tx(cdev, 1);
+			frame_len = m_can_tx_update_stats(cdev, 0, timestamp);
+			m_can_finish_tx(cdev, 1, frame_len);
 		}
 	} else  {
 		if (ir & (IR_TEFN | IR_TEFW)) {
@@ -1714,6 +1725,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 	u32 cccr, fdflags;
 	int err;
 	u32 putidx;
+	unsigned int frame_len = can_skb_get_frame_len(skb);
 
 	/* Generate ID field for TX buffer Element */
 	/* Common to all supported M_CAN versions */
@@ -1759,7 +1771,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		}
 		m_can_write(cdev, M_CAN_TXBTIE, 0x1);
 
-		can_put_echo_skb(skb, dev, 0, 0);
+		can_put_echo_skb(skb, dev, 0, frame_len);
 
 		m_can_write(cdev, M_CAN_TXBAR, 0x1);
 		/* End of xmit function for version 3.0.x */
@@ -1797,7 +1809,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		/* Push loopback echo.
 		 * Will be looped back on TX interrupt based on message marker
 		 */
-		can_put_echo_skb(skb, dev, putidx, 0);
+		can_put_echo_skb(skb, dev, putidx, frame_len);
 
 		/* Enable TX FIFO element to start transfer  */
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
@@ -1868,14 +1880,23 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 				    struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
+	netdev_tx_t ret;
+	unsigned int frame_len;
 
 	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
+	frame_len = can_skb_get_frame_len(skb);
+
 	if (cdev->is_peripheral)
-		return m_can_start_peripheral_xmit(cdev, skb);
+		ret = m_can_start_peripheral_xmit(cdev, skb);
 	else
-		return m_can_start_fast_xmit(cdev, skb);
+		ret = m_can_start_fast_xmit(cdev, skb);
+
+	if (ret == NETDEV_TX_OK)
+		netdev_sent_queue(dev, frame_len);
+
+	return ret;
 }
 
 static int m_can_open(struct net_device *dev)
-- 
2.40.1

[PATCH v5 12/12] can: m_can: Implement transmit submission coalescing

[Markus Schneider-Pargmann]

m_can supports submitting multiple transmits with one register write.
This is an interesting option to reduce the number of SPI transfers for
peripheral chips.

The m_can_tx_op is extended with a bool that signals if it is the last
transmission and the submit should be executed immediately.

The worker then writes the skb to the FIFO and submits it only if the
submit bool is set. If it isn't set, the worker will write the next skb
which is waiting in the workqueue to the FIFO, etc.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---

Notes:
    Notes:
    - I put this behind the tx-frames ethtool coalescing option as we do
      wait before submitting packages but it is something different than the
      tx-frames-irq option. I am not sure if this is the correct option,
      please let me know.

 drivers/net/can/m_can/m_can.c | 55 ++++++++++++++++++++++++++++++++---
 drivers/net/can/m_can/m_can.h |  6 ++++
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index b775ee8e5ff5..aa8c5a8445de 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1515,6 +1515,9 @@ static int m_can_start(struct net_device *dev)
 	if (ret)
 		return ret;
 
+	netdev_queue_set_dql_min_limit(netdev_get_tx_queue(cdev->net, 0),
+				       cdev->tx_max_coalesced_frames);
+
 	cdev->can.state = CAN_STATE_ERROR_ACTIVE;
 
 	m_can_enable_all_interrupts(cdev);
@@ -1811,8 +1814,13 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		 */
 		can_put_echo_skb(skb, dev, putidx, frame_len);
 
-		/* Enable TX FIFO element to start transfer  */
-		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
+		if (cdev->is_peripheral) {
+			/* Delay enabling TX FIFO element */
+			cdev->tx_peripheral_submit |= BIT(putidx);
+		} else {
+			/* Enable TX FIFO element to start transfer  */
+			m_can_write(cdev, M_CAN_TXBAR, BIT(putidx));
+		}
 		cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
 					0 : cdev->tx_fifo_putidx);
 	}
@@ -1825,6 +1833,17 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 	return NETDEV_TX_BUSY;
 }
 
+static void m_can_tx_submit(struct m_can_classdev *cdev)
+{
+	if (cdev->version == 30)
+		return;
+	if (!cdev->is_peripheral)
+		return;
+
+	m_can_write(cdev, M_CAN_TXBAR, cdev->tx_peripheral_submit);
+	cdev->tx_peripheral_submit = 0;
+}
+
 static void m_can_tx_work_queue(struct work_struct *ws)
 {
 	struct m_can_tx_op *op = container_of(ws, struct m_can_tx_op, work);
@@ -1833,11 +1852,15 @@ static void m_can_tx_work_queue(struct work_struct *ws)
 
 	op->skb = NULL;
 	m_can_tx_handler(cdev, skb);
+	if (op->submit)
+		m_can_tx_submit(cdev);
 }
 
-static void m_can_tx_queue_skb(struct m_can_classdev *cdev, struct sk_buff *skb)
+static void m_can_tx_queue_skb(struct m_can_classdev *cdev, struct sk_buff *skb,
+			       bool submit)
 {
 	cdev->tx_ops[cdev->next_tx_op].skb = skb;
+	cdev->tx_ops[cdev->next_tx_op].submit = submit;
 	queue_work(cdev->tx_wq, &cdev->tx_ops[cdev->next_tx_op].work);
 
 	++cdev->next_tx_op;
@@ -1849,6 +1872,7 @@ static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
 					       struct sk_buff *skb)
 {
 	netdev_tx_t err;
+	bool submit;
 
 	if (cdev->can.state == CAN_STATE_BUS_OFF) {
 		m_can_clean(cdev->net);
@@ -1859,7 +1883,15 @@ static netdev_tx_t m_can_start_peripheral_xmit(struct m_can_classdev *cdev,
 	if (err != NETDEV_TX_OK)
 		return err;
 
-	m_can_tx_queue_skb(cdev, skb);
+	++cdev->nr_txs_without_submit;
+	if (cdev->nr_txs_without_submit >= cdev->tx_max_coalesced_frames ||
+	    !netdev_xmit_more()) {
+		cdev->nr_txs_without_submit = 0;
+		submit = true;
+	} else {
+		submit = false;
+	}
+	m_can_tx_queue_skb(cdev, skb, submit);
 
 	return NETDEV_TX_OK;
 }
@@ -1991,6 +2023,7 @@ static int m_can_get_coalesce(struct net_device *dev,
 
 	ec->rx_max_coalesced_frames_irq = cdev->rx_max_coalesced_frames_irq;
 	ec->rx_coalesce_usecs_irq = cdev->rx_coalesce_usecs_irq;
+	ec->tx_max_coalesced_frames = cdev->tx_max_coalesced_frames;
 	ec->tx_max_coalesced_frames_irq = cdev->tx_max_coalesced_frames_irq;
 	ec->tx_coalesce_usecs_irq = cdev->tx_coalesce_usecs_irq;
 
@@ -2035,6 +2068,18 @@ static int m_can_set_coalesce(struct net_device *dev,
 		netdev_err(dev, "tx-frames-irq and tx-usecs-irq can only be set together\n");
 		return -EINVAL;
 	}
+	if (ec->tx_max_coalesced_frames > cdev->mcfg[MRAM_TXE].num) {
+		netdev_err(dev, "tx-frames %u greater than the TX event FIFO %u\n",
+			   ec->tx_max_coalesced_frames,
+			   cdev->mcfg[MRAM_TXE].num);
+		return -EINVAL;
+	}
+	if (ec->tx_max_coalesced_frames > cdev->mcfg[MRAM_TXB].num) {
+		netdev_err(dev, "tx-frames %u greater than the TX FIFO %u\n",
+			   ec->tx_max_coalesced_frames,
+			   cdev->mcfg[MRAM_TXB].num);
+		return -EINVAL;
+	}
 	if (ec->rx_coalesce_usecs_irq != 0 && ec->tx_coalesce_usecs_irq != 0 &&
 	    ec->rx_coalesce_usecs_irq != ec->tx_coalesce_usecs_irq) {
 		netdev_err(dev, "rx-usecs-irq %u needs to be equal to tx-usecs-irq %u if both are enabled\n",
@@ -2045,6 +2090,7 @@ static int m_can_set_coalesce(struct net_device *dev,
 
 	cdev->rx_max_coalesced_frames_irq = ec->rx_max_coalesced_frames_irq;
 	cdev->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
+	cdev->tx_max_coalesced_frames = ec->tx_max_coalesced_frames;
 	cdev->tx_max_coalesced_frames_irq = ec->tx_max_coalesced_frames_irq;
 	cdev->tx_coalesce_usecs_irq = ec->tx_coalesce_usecs_irq;
 
@@ -2062,6 +2108,7 @@ static const struct ethtool_ops m_can_ethtool_ops = {
 	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
 		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ |
 		ETHTOOL_COALESCE_TX_USECS_IRQ |
+		ETHTOOL_COALESCE_TX_MAX_FRAMES |
 		ETHTOOL_COALESCE_TX_MAX_FRAMES_IRQ,
 	.get_ts_info = ethtool_op_get_ts_info,
 	.get_coalesce = m_can_get_coalesce,
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index 5c182aece15c..54af26a94042 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -74,6 +74,7 @@ struct m_can_tx_op {
 	struct m_can_classdev *cdev;
 	struct work_struct work;
 	struct sk_buff *skb;
+	bool submit;
 };
 
 struct m_can_classdev {
@@ -103,6 +104,7 @@ struct m_can_classdev {
 	u32 active_interrupts;
 	u32 rx_max_coalesced_frames_irq;
 	u32 rx_coalesce_usecs_irq;
+	u32 tx_max_coalesced_frames;
 	u32 tx_max_coalesced_frames_irq;
 	u32 tx_coalesce_usecs_irq;
 
@@ -117,6 +119,10 @@ struct m_can_classdev {
 	int tx_fifo_size;
 	int next_tx_op;
 
+	int nr_txs_without_submit;
+	/* bitfield of fifo elements that will be submitted together */
+	u32 tx_peripheral_submit;
+
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };
 
-- 
2.40.1

Re: [PATCH v5 12/12] can: m_can: Implement transmit submission coalescing

[Simon Horman]

On Tue, Jul 18, 2023 at 09:57:08AM +0200, Markus Schneider-Pargmann wrote:
> m_can supports submitting multiple transmits with one register write.
> This is an interesting option to reduce the number of SPI transfers for
> peripheral chips.
> 
> The m_can_tx_op is extended with a bool that signals if it is the last
> transmission and the submit should be executed immediately.
> 
> The worker then writes the skb to the FIFO and submits it only if the
> submit bool is set. If it isn't set, the worker will write the next skb
> which is waiting in the workqueue to the FIFO, etc.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

Re: [PATCH v5 12/12] can: m_can: Implement transmit submission coalescing

[Markus Schneider-Pargmann]

Hi Simon,

On Thu, Jul 20, 2023 at 04:58:49PM +0100, Simon Horman wrote:
> On Tue, Jul 18, 2023 at 09:57:08AM +0200, Markus Schneider-Pargmann wrote:
> > m_can supports submitting multiple transmits with one register write.
> > This is an interesting option to reduce the number of SPI transfers for
> > peripheral chips.
> > 
> > The m_can_tx_op is extended with a bool that signals if it is the last
> > transmission and the submit should be executed immediately.
> > 
> > The worker then writes the skb to the FIFO and submits it only if the
> > submit bool is set. If it isn't set, the worker will write the next skb
> > which is waiting in the workqueue to the FIFO, etc.
> > 
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> 
> Reviewed-by: Simon Horman <simon.horman@corigine.com>

Thank you for your reviews!

Best,
Markus

Re: [PATCH v5 00/12] can: m_can: Optimizations for m_can/tcan part 2

[Markus Schneider-Pargmann]

Hi Marc,

did you have some time to review this series? Anything I should rework?

Thanks,
Markus

On Tue, Jul 18, 2023 at 09:56:56AM +0200, Markus Schneider-Pargmann wrote:
> Hi Marc, Simon and everyone,
> 
> v5 got a rebase on v6.5 with some small style fixes as pointed out in v4.
> 
> It is tested on tcan455x but I don't have hardware with mcan on the SoC
> myself so any testing is appreciated.
> 
> The series implements many small and bigger throughput improvements and
> adds rx/tx coalescing at the end.
> 
> Based on v6.5-rc1. Also available at
> https://gitlab.baylibre.com/msp8/linux/-/tree/topic/mcan-optimization/v6.5?ref_type=heads
> 
> Best,
> Markus
> 
> Changes in v5:
> - Add back parenthesis in m_can_set_coalesce(). This will make
>   checkpatch unhappy but gcc happy.
> - Remove unused fifo_header variable in m_can_tx_handler().
> - Rebased to v6.5-rc1
> 
> Changes in v4:
> - Create and use struct m_can_fifo_element in m_can_tx_handler
> - Fix memcpy_and_pad to copy the full buffer
> - Fixed a few checkpatch warnings
> - Change putidx to be unsigned
> - Print hard_xmit error only once when TX FIFO is full
> 
> Changes in v3:
> - Remove parenthesis in error messages
> - Use memcpy_and_pad for buffer copy in 'can: m_can: Write transmit
>   header and data in one transaction'.
> - Replace spin_lock with spin_lock_irqsave. I got a report of a
>   interrupt that was calling start_xmit just after the netqueue was
>   woken up before the locked region was exited. spin_lock_irqsave should
>   fix this. I attached the full stack at the end of the mail if someone
>   wants to know.
> - Rebased to v6.3-rc1.
> - Removed tcan4x5x patches from this series.
> 
> Changes in v2:
> - Rebased on v6.2-rc5
> - Fixed missing/broken accounting for non peripheral m_can devices.
> 
> previous versions:
> v1 - https://lore.kernel.org/lkml/20221221152537.751564-1-msp@baylibre.com
> v2 - https://lore.kernel.org/lkml/20230125195059.630377-1-msp@baylibre.com
> v3 - https://lore.kernel.org/lkml/20230315110546.2518305-1-msp@baylibre.com/
> v4 - https://lore.kernel.org/lkml/20230621092350.3130866-1-msp@baylibre.com/
> 
> Markus Schneider-Pargmann (12):
>   can: m_can: Write transmit header and data in one transaction
>   can: m_can: Implement receive coalescing
>   can: m_can: Implement transmit coalescing
>   can: m_can: Add rx coalescing ethtool support
>   can: m_can: Add tx coalescing ethtool support
>   can: m_can: Use u32 for putidx
>   can: m_can: Cache tx putidx
>   can: m_can: Use the workqueue as queue
>   can: m_can: Introduce a tx_fifo_in_flight counter
>   can: m_can: Use tx_fifo_in_flight for netif_queue control
>   can: m_can: Implement BQL
>   can: m_can: Implement transmit submission coalescing
> 
>  drivers/net/can/m_can/m_can.c | 517 +++++++++++++++++++++++++---------
>  drivers/net/can/m_can/m_can.h |  35 ++-
>  2 files changed, 418 insertions(+), 134 deletions(-)
> 
> 
> base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
> -- 
> 2.40.1
> 

Re: [PATCH v5 00/12] can: m_can: Optimizations for m_can/tcan part 2

[Martin Hundebøll]

On Tue, 2023-07-18 at 09:56 +0200, Markus Schneider-Pargmann wrote:
> Hi Marc, Simon and everyone,
> 
> v5 got a rebase on v6.5 with some small style fixes as pointed out in
> v4.
> 
> It is tested on tcan455x but I don't have hardware with mcan on the
> SoC
> myself so any testing is appreciated.
> 
> The series implements many small and bigger throughput improvements
> and
> adds rx/tx coalescing at the end.
> 
> Based on v6.5-rc1. Also available at
> https://gitlab.baylibre.com/msp8/linux/-/tree/topic/mcan-optimization/v6.5?ref_type=heads

For the whole series:
Tested-by: Martin Hundebøll <martin@geanix.com>

Thanks,
Martin

> Changes in v5:
> - Add back parenthesis in m_can_set_coalesce(). This will make
>   checkpatch unhappy but gcc happy.
> - Remove unused fifo_header variable in m_can_tx_handler().
> - Rebased to v6.5-rc1
> 
> Changes in v4:
> - Create and use struct m_can_fifo_element in m_can_tx_handler
> - Fix memcpy_and_pad to copy the full buffer
> - Fixed a few checkpatch warnings
> - Change putidx to be unsigned
> - Print hard_xmit error only once when TX FIFO is full
> 
> Changes in v3:
> - Remove parenthesis in error messages
> - Use memcpy_and_pad for buffer copy in 'can: m_can: Write transmit
>   header and data in one transaction'.
> - Replace spin_lock with spin_lock_irqsave. I got a report of a
>   interrupt that was calling start_xmit just after the netqueue was
>   woken up before the locked region was exited. spin_lock_irqsave
> should
>   fix this. I attached the full stack at the end of the mail if
> someone
>   wants to know.
> - Rebased to v6.3-rc1.
> - Removed tcan4x5x patches from this series.
> 
> Changes in v2:
> - Rebased on v6.2-rc5
> - Fixed missing/broken accounting for non peripheral m_can devices.
> 
> previous versions:
> v1 -
> https://lore.kernel.org/lkml/20221221152537.751564-1-msp@baylibre.com
> v2 -
> https://lore.kernel.org/lkml/20230125195059.630377-1-msp@baylibre.com
> v3 -
> https://lore.kernel.org/lkml/20230315110546.2518305-1-msp@baylibre.com/
> v4 -
> https://lore.kernel.org/lkml/20230621092350.3130866-1-msp@baylibre.com/
> 
> Markus Schneider-Pargmann (12):
>   can: m_can: Write transmit header and data in one transaction
>   can: m_can: Implement receive coalescing
>   can: m_can: Implement transmit coalescing
>   can: m_can: Add rx coalescing ethtool support
>   can: m_can: Add tx coalescing ethtool support
>   can: m_can: Use u32 for putidx
>   can: m_can: Cache tx putidx
>   can: m_can: Use the workqueue as queue
>   can: m_can: Introduce a tx_fifo_in_flight counter
>   can: m_can: Use tx_fifo_in_flight for netif_queue control
>   can: m_can: Implement BQL
>   can: m_can: Implement transmit submission coalescing
> 
>  drivers/net/can/m_can/m_can.c | 517 +++++++++++++++++++++++++-------
> --
>  drivers/net/can/m_can/m_can.h |  35 ++-
>  2 files changed, 418 insertions(+), 134 deletions(-)
> 
> 
> base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5

Re: [PATCH v5 00/12] can: m_can: Optimizations for m_can/tcan part 2

[Markus Schneider-Pargmann]

On Wed, Aug 23, 2023 at 08:51:48AM +0200, Martin Hundebøll wrote:
> On Tue, 2023-07-18 at 09:56 +0200, Markus Schneider-Pargmann wrote:
> > Hi Marc, Simon and everyone,
> > 
> > v5 got a rebase on v6.5 with some small style fixes as pointed out in
> > v4.
> > 
> > It is tested on tcan455x but I don't have hardware with mcan on the
> > SoC
> > myself so any testing is appreciated.
> > 
> > The series implements many small and bigger throughput improvements
> > and
> > adds rx/tx coalescing at the end.
> > 
> > Based on v6.5-rc1. Also available at
> > https://gitlab.baylibre.com/msp8/linux/-/tree/topic/mcan-optimization/v6.5?ref_type=heads
> 
> For the whole series:
> Tested-by: Martin Hundebøll <martin@geanix.com>

Thank you Martin!

Best,
Markus

> 
> Thanks,
> Martin
> 
> > Changes in v5:
> > - Add back parenthesis in m_can_set_coalesce(). This will make
> >   checkpatch unhappy but gcc happy.
> > - Remove unused fifo_header variable in m_can_tx_handler().
> > - Rebased to v6.5-rc1
> > 
> > Changes in v4:
> > - Create and use struct m_can_fifo_element in m_can_tx_handler
> > - Fix memcpy_and_pad to copy the full buffer
> > - Fixed a few checkpatch warnings
> > - Change putidx to be unsigned
> > - Print hard_xmit error only once when TX FIFO is full
> > 
> > Changes in v3:
> > - Remove parenthesis in error messages
> > - Use memcpy_and_pad for buffer copy in 'can: m_can: Write transmit
> >   header and data in one transaction'.
> > - Replace spin_lock with spin_lock_irqsave. I got a report of a
> >   interrupt that was calling start_xmit just after the netqueue was
> >   woken up before the locked region was exited. spin_lock_irqsave
> > should
> >   fix this. I attached the full stack at the end of the mail if
> > someone
> >   wants to know.
> > - Rebased to v6.3-rc1.
> > - Removed tcan4x5x patches from this series.
> > 
> > Changes in v2:
> > - Rebased on v6.2-rc5
> > - Fixed missing/broken accounting for non peripheral m_can devices.
> > 
> > previous versions:
> > v1 -
> > https://lore.kernel.org/lkml/20221221152537.751564-1-msp@baylibre.com
> > v2 -
> > https://lore.kernel.org/lkml/20230125195059.630377-1-msp@baylibre.com
> > v3 -
> > https://lore.kernel.org/lkml/20230315110546.2518305-1-msp@baylibre.com/
> > v4 -
> > https://lore.kernel.org/lkml/20230621092350.3130866-1-msp@baylibre.com/
> > 
> > Markus Schneider-Pargmann (12):
> >   can: m_can: Write transmit header and data in one transaction
> >   can: m_can: Implement receive coalescing
> >   can: m_can: Implement transmit coalescing
> >   can: m_can: Add rx coalescing ethtool support
> >   can: m_can: Add tx coalescing ethtool support
> >   can: m_can: Use u32 for putidx
> >   can: m_can: Cache tx putidx
> >   can: m_can: Use the workqueue as queue
> >   can: m_can: Introduce a tx_fifo_in_flight counter
> >   can: m_can: Use tx_fifo_in_flight for netif_queue control
> >   can: m_can: Implement BQL
> >   can: m_can: Implement transmit submission coalescing
> > 
> >  drivers/net/can/m_can/m_can.c | 517 +++++++++++++++++++++++++-------
> > --
> >  drivers/net/can/m_can/m_can.h |  35 ++-
> >  2 files changed, 418 insertions(+), 134 deletions(-)
> > 
> > 
> > base-commit: 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5
>