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Subject[PATCH 11/15] can: m_can: Batch acknowledge transmit events
Date
Transmit events from the txe fifo can be batch acknowledged by
acknowledging the last read txe fifo item. This will save txe_count
writes which is important for peripheral chips.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
drivers/net/can/m_can/m_can.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 6179b9e815ed..347ba8e7d1b3 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1019,7 +1019,9 @@ static int m_can_echo_tx_event(struct net_device *dev)
u32 txe_count = 0;
u32 m_can_txefs;
u32 fgi = 0;
+ int ack_fgi = -1;
int i = 0;
+ int err = 0;
unsigned int msg_mark;

struct m_can_classdev *cdev = netdev_priv(dev);
@@ -1034,21 +1036,18 @@ static int m_can_echo_tx_event(struct net_device *dev)
/* Get and process all sent elements */
for (i = 0; i < txe_count; i++) {
u32 txe, timestamp = 0;
- int err;

/* get message marker, timestamp */
err = m_can_txe_fifo_read(cdev, fgi, 4, &txe);
if (err) {
netdev_err(dev, "TXE FIFO read returned %d\n", err);
- return err;
+ break;
}

msg_mark = FIELD_GET(TX_EVENT_MM_MASK, txe);
timestamp = FIELD_GET(TX_EVENT_TXTS_MASK, txe) << 16;

- /* ack txe element */
- m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
- fgi));
+ ack_fgi = fgi;
fgi = (++fgi >= cdev->mcfg[MRAM_TXE].num ? 0 : fgi);
--cdev->tx_fifo_in_flight;

@@ -1056,7 +1055,11 @@ static int m_can_echo_tx_event(struct net_device *dev)
m_can_tx_update_stats(cdev, msg_mark, timestamp);
}

- return 0;
+ if (ack_fgi != -1)
+ m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
+ ack_fgi));
+
+ return err;
}

static irqreturn_t m_can_isr(int irq, void *dev_id)
--
2.38.1
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