On 18 September 2017 at 20:50, Andrey Smirnov <andrew.smir...@gmail.com> wrote:
> Save some computation time and avoid calculating CRC's frame
>
> Cc: Peter Maydell <peter.mayd...@linaro.org>
> Cc: Jason Wang <jasow...@redhat.com>
> Cc: qemu-devel@nongnu.org
> Cc: qemu-...@nongnu.org
> Cc: yurov...@gmail.com
> Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
> ---
> hw/net/imx_fec.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c
> index 88b4b049d7..75822344fc 100644
> --- a/hw/net/imx_fec.c
> +++ b/hw/net/imx_fec.c
> @@ -1032,9 +1032,7 @@ static ssize_t imx_enet_receive(NetClientState *nc,
> const uint8_t *buf,
> IMXENETBufDesc bd;
> uint32_t flags = 0;
> uint32_t addr;
> - uint32_t crc;
> uint32_t buf_addr;
> - uint8_t *crc_ptr;
> unsigned int buf_len;
> size_t size = len;
>
> @@ -1048,8 +1046,6 @@ static ssize_t imx_enet_receive(NetClientState *nc,
> const uint8_t *buf,
>
> /* 4 bytes for the CRC. */
> size += 4;
> - crc = cpu_to_be32(crc32(~0, buf, size));
> - crc_ptr = (uint8_t *) &crc;
>
> /* Huge frames are truncted. */
> if (size > ENET_MAX_FRAME_SIZE) {
> @@ -1090,9 +1086,10 @@ static ssize_t imx_enet_receive(NetClientState *nc,
> const uint8_t *buf,
> dma_memory_write(&address_space_memory, buf_addr, buf, buf_len);
> buf += buf_len;
> if (size < 4) {
> + const uint8_t zeros[4] = { 0 };
> +
> dma_memory_write(&address_space_memory, buf_addr + buf_len,
> - crc_ptr, 4 - size);
> - crc_ptr += 4 - size;
> + zeros, 4 - size);
> }
> bd.flags &= ~ENET_BD_E;
> if (size == 0) {
This looks a bit odd. Doesn't the hardware calculate the CRC here?
thanks
-- PMM
