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Subject[PATCH v3 06/16] can: m_can: Write transmit header and data in one transaction
Date
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 | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index a5003435802b..35a2332464e5 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1681,6 +1681,8 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
m_can_write(cdev, M_CAN_TXBAR, 0x1);
/* End of xmit function for version 3.0.x */
} else {
+ char buf[TXB_ELEMENT_SIZE];
+ u8 len_padded = DIV_ROUND_UP(cf->len, 4);
/* Transmit routine for version >= v3.1.x */

txfqs = m_can_read(cdev, M_CAN_TXFQS);
@@ -1720,12 +1722,11 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
fifo_header.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;
+ memcpy(buf, &fifo_header, 8);
+ memcpy_and_pad(&buf[8], len_padded, &cf->data, cf->len, 0);

- err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA,
- cf->data, DIV_ROUND_UP(cf->len, 4));
+ err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID,
+ buf, 2 + len_padded);
if (err)
goto out_fail;

--
2.39.2
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