On Wed, Mar 15, 2023 at 12:05:36PM +0100, 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@xxxxxxxxxxxx>
Thanks for addressing my comments on v2.
> ---
> 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);
I'm probably missing something obvious here but I'm seeing:
* len_padded is the number of 4-byte words
* but the 2nd argument to memcpy_and_pad should be a length in bytes
* so perhaps it should be: len_padded * 4
>
> - 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);
This part looks good to me :)
> if (err)
> goto out_fail;
>
> --
> 2.39.2
>
