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Re: [Qemu-devel] [PATCH V2 2/2] Fix lan9118 buffer length handling


From: Peter Crosthwaite
Subject: Re: [Qemu-devel] [PATCH V2 2/2] Fix lan9118 buffer length handling
Date: Wed, 8 Jan 2014 14:50:46 +1000

On Wed, Jan 8, 2014 at 2:19 PM, Roy Franz <address@hidden> wrote:
> The 9118 ethernet controller supports transmission of multi-buffer packets
> with arbitrary byte alignment of the start and end bytes.  All writes to
> the packet fifo are 32 bits, so the controller discards bytes at the beginning
> and end of each buffer based on the 'Data start offset' and 'Buffer size'
> of the TX command 'A' format.
>
> This patch uses the provided buffer length to limit the bytes transmitted.
> Previously all the bytes of the last 32-bit word written to the TX fifo
> were added to the internal transmit buffer structure resulting in more bytes
> being transmitted than were submitted to the hardware in the command.  This
> resulted in extra bytes being inserted into the middle of multi-buffer
> packets when the non-final buffers had non-32bit aligned ending addresses.
>
> Signed-off-by: Roy Franz <address@hidden>

Reviewed-by: Peter Crosthwaite <address@hidden>

> ---
>  hw/net/lan9118.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/net/lan9118.c b/hw/net/lan9118.c
> index bb0c503..e528290 100644
> --- a/hw/net/lan9118.c
> +++ b/hw/net/lan9118.c
> @@ -763,7 +763,7 @@ static void tx_fifo_push(lan9118_state *s, uint32_t val)
>          if (s->txp->buffer_size <= 0 && s->txp->pad != 0) {
>              s->txp->pad--;
>          } else {
> -            n = 4;
> +            n = MIN(4, s->txp->buffer_size + s->txp->offset);
>              while (s->txp->offset) {
>                  val >>= 8;
>                  n--;
> --
> 1.7.10.4
>
>



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