[U-Boot] [PATCH 11/14][v2] driver/ldpaa_eth: Retry enqueue if portal was busy

[Joe Hershberger]

Hi Prabhakar,

On Thu, Jun 11, 2015 at 4:03 AM, Prabhakar Kushwaha
<prabhakar at freescale.com> wrote:
> Do not immediately return if the enqueue function returns -EBUSY; re-try
> mulitple times.
>
> if timeout occures, release the buffer.
>
> Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
> ---
> Changes for v2: Sending as it is for patchset
>
>  drivers/net/ldpaa_eth/ldpaa_eth.c | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ldpaa_eth/ldpaa_eth.c b/drivers/net/ldpaa_eth/ldpaa_eth.c
> index 5636511..2716f6c 100644
> --- a/drivers/net/ldpaa_eth/ldpaa_eth.c
> +++ b/drivers/net/ldpaa_eth/ldpaa_eth.c
> @@ -221,8 +221,11 @@ static int ldpaa_eth_tx(struct eth_device *net_dev, void *buf, int len)
>         struct dpaa_fd fd;
>         u64 buffer_start;
>         int data_offset, err;
> +       u32 timeo = (CONFIG_SYS_HZ * 10) / 1000;
> +       u32 time_start;
>         struct qbman_swp *swp = dflt_dpio->sw_portal;
>         struct qbman_eq_desc ed;
> +       struct qbman_release_desc releasedesc;
>
>         /* Setup the FD fields */
>         memset(&fd, 0, sizeof(fd));
> @@ -258,9 +261,18 @@ static int ldpaa_eth_tx(struct eth_device *net_dev, void *buf, int len)
>         qbman_eq_desc_clear(&ed);
>         qbman_eq_desc_set_no_orp(&ed, 0);
>         qbman_eq_desc_set_qd(&ed, priv->tx_qdid, priv->tx_flow_id, 0);
> -       err = qbman_swp_enqueue(swp, &ed, (const struct qbman_fd *)(&fd));
> +
> +       time_start = get_timer(0);
> +
> +       while (get_timer(time_start) < timeo) {
> +               err = qbman_swp_enqueue(swp, &ed,
> +                               (const struct qbman_fd *)(&fd));
> +               if (err != -EBUSY)
> +                       break;
> +       }
> +
>         if (err < 0)
> -               printf("error enqueueing Tx frame\n");
> +               goto error;
>
>         mdelay(1);
>
> @@ -269,6 +281,16 @@ static int ldpaa_eth_tx(struct eth_device *net_dev, void *buf, int len)
>                 printf("error Tx Conf frame\n");
>
>         return err;
> +
> +error:
> +       qbman_release_desc_clear(&releasedesc);
> +       qbman_release_desc_set_bpid(&releasedesc, dflt_dpbp->dpbp_attr.bpid);
> +       do {
> +               /* Release buffer into the QBMAN */
> +               err = qbman_swp_release(swp, &releasedesc, &buffer_start, 1);
> +       } while (err == -EBUSY);

Are you sure it's 100% safe to have this infinite loop here? Is there
a guarantee that qbman_swp_release() will stop returning -EBUSY?

> +
> +       return err;
>  }
>
>  static int ldpaa_eth_open(struct eth_device *net_dev, bd_t *bd)
> --
> 1.9.1
>
>
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