[U-Boot] [PATCH] dm: eth: Provide a way for drivers to manage packet buffers

[Simon Glass]

Hi Joe,

On 30 March 2015 at 14:44, Joe Hershberger <joe.hershberger at ni.com> wrote:
> Some drivers need a chance to manage their receive buffers after the
> packet has been handled by the network stack. Add an operation that
> will allow the driver to be called in that case.
>
> Reported-by: Simon Glass <sjg at chromium.org>
> Signed-off-by: Joe Hershberger <joe.hershberger at ni.com>
> ---
> This patch depends on dm/next
>
>  include/net.h | 4 ++++
>  net/eth.c     | 8 ++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/include/net.h b/include/net.h
> index e7f28d7..f9df532 100644
> --- a/include/net.h
> +++ b/include/net.h
> @@ -98,6 +98,9 @@ struct eth_pdata {
>   * recv: Check if the hardware received a packet. If so, set the pointer to the
>   *      packet buffer in the packetp parameter. If not, return an error or 0 to
>   *      indicate that the hardware receive FIFO is empty
> + * free_pkt: Give the driver an opportunity to manage its packet buffer memory
> + *          when the network stack is finished processing it. This will only be
> + *          called when a packet was successfully returned from recv - optional
>   * stop: Stop the hardware from looking for packets - may be called even if
>   *      state == PASSIVE
>   * mcast: Join or leave a multicast group (for TFTP) - optional
> @@ -113,6 +116,7 @@ struct eth_ops {
>         int (*start)(struct udevice *dev);
>         int (*send)(struct udevice *dev, void *packet, int length);
>         int (*recv)(struct udevice *dev, uchar **packetp);
> +       int (*free_pkt)(struct udevice *dev, uchar *packet, int length);
>         void (*stop)(struct udevice *dev);
>  #ifdef CONFIG_MCAST_TFTP
>         int (*mcast)(struct udevice *dev, const u8 *enetaddr, int join);
> diff --git a/net/eth.c b/net/eth.c
> index 13b7723..889ad8f 100644
> --- a/net/eth.c
> +++ b/net/eth.c
> @@ -342,10 +342,14 @@ int eth_rx(void)
>         /* Process up to 32 packets at one time */
>         for (i = 0; i < 32; i++) {
>                 ret = eth_get_ops(current)->recv(current, &packet);
> -               if (ret > 0)
> +               if (ret > 0) {

To match the old net stack behaviour I wonder if we should process the
packet when it is length 0, and require recv() to return -EAGAIN when
there is no packet? At least with designware, it processes a 0-length
packet for some reason, and we need to call free_pkt() in that case.

>                         net_process_received_packet(packet, ret);
> -               else
> +                       if (eth_get_ops(current)->free_pkt)
> +                               eth_get_ops(current)->free_pkt(current, packet,
> +                                                              ret);
> +               } else {
>                         break;
> +               }
>         }
>         if (ret == -EAGAIN)
>                 ret = 0;
> --
> 1.7.11.5
>

Tested on pcduino3:

Tested-by: Simon Glass <sjg at chromium.org>
Acked-by: Simon Glass <sjg at chromium.org>

Regards,
Simon