Hi Simon,
On Thu, Mar 16, 2023 at 10:27:41AM +0100, Simon Horman wrote:
> 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
Thank you Simon for all the reviews, finally some time to continue on
this:
Thanks for pointing this out. I updated my script used for testing so I
catch something like this the next time. I will be using
TXB_ELEMENT_SIZE - 8 to reflect the buffer size and the 8 byte offset.
Best,
Markus
>
> >
> > - 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
> >
