Merge patch series "can: m_can: Optimizations for m_can/tcan part 2"

Markus Schneider-Pargmann <msp@baylibre.com> says:

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

Changes in v7:
- Rebased to v6.8-rc1
- Fixed NULL pointer dereference in m_can_clean() on am62 that happened
  when doing ip link up, ip link down, ip link up
- Fixed a racecondition on am62 observed with high throughput tests.
  netdev_completed_queue() was called before netdev_sent_queue() as the
  interrupt was processed so fast. netdev_sent_queue() is now reported
  before the actual sent is done.
- Fixed an initializing issue on am62 where active interrupts are
  getting lost between runs. Fixed by resetting cdev->active_interrupts
  in m_can_disable_all_interrupts()
- Removed m_can_start_fast_xmit() because of a reordering of operations
  due to above mentioned race condition

Changes in v6:
- Rebased to v6.6-rc2
- Added two small changes for the newly integrated polling feature
- Reuse the polling hrtimer for coalescing as the timer used for
  coalescing has a similar purpose as the one for polling. Also polling
  and coalescing will never be active at the same time.

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
v5 - https://lore.kernel.org/lkml/20230718075708.958094-1-msp@baylibre.com
v6 - https://lore.kernel.org/lkml/20230929141304.3934380-1-msp@baylibre.com

Link: https://lore.kernel.org/all/20240207093220.2681425-1-msp@baylibre.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/m_can.h

@@ -70,6 +70,13 @@ 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;
+	bool submit;
+};
+
 struct m_can_classdev {
 	struct can_priv can;
 	struct can_rx_offload offload;
@@ -80,10 +87,10 @@ 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;
 
+	ktime_t irq_timer_wait;
+
 	struct m_can_ops *ops;
 
 	int version;
@@ -92,6 +99,29 @@ 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;
+	u32 tx_max_coalesced_frames;
+	u32 tx_max_coalesced_frames_irq;
+	u32 tx_coalesce_usecs_irq;
+
+	// 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;
+
+	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];
 
 	struct hrtimer hrtimer;

drivers/net/can/m_can/m_can_platform.c

@@ -109,10 +109,6 @@ static int m_can_plat_probe(struct platform_device *pdev)
 			ret = irq;
 			goto probe_fail;
 		}
-	} else {
-		dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
-		hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
-			     HRTIMER_MODE_REL_PINNED);
 	}
 
 	/* message ram could be shared */