[PATCH 5/6] net: dwc_eth_qos: Invalidate RX packet DMA buffer

[Ramon Fried]

On Mon, Mar 23, 2020 at 3:45 AM Marek Vasut <marex at denx.de> wrote:
>
> This patch prevents an issue where the RX packet might have been
> accessed by the CPU, which now has cached data from the packet in
> the caches and possibly various write buffers, and these data may
> be evicted from the caches into the DRAM while the buffer is also
> written by the DMA.
>
> By invalidating the buffer after the CPU accessed it and before the
> DMA populates the buffer, it is assured that the buffer will not be
> corrupted.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Joe Hershberger <joe.hershberger at ni.com>
> Cc: Patrice Chotard <patrice.chotard at st.com>
> Cc: Patrick Delaunay <patrick.delaunay at st.com>
> Cc: Ramon Fried <rfried.dev at gmail.com>
> Cc: Stephen Warren <swarren at nvidia.com>
> ---
>  drivers/net/dwc_eth_qos.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/dwc_eth_qos.c b/drivers/net/dwc_eth_qos.c
> index e40c461278..7dadb10fe7 100644
> --- a/drivers/net/dwc_eth_qos.c
> +++ b/drivers/net/dwc_eth_qos.c
> @@ -1430,6 +1430,9 @@ static int eqos_free_pkt(struct udevice *dev, uchar *packet, int length)
>         }
>
>         rx_desc = &(eqos->rx_descs[eqos->rx_desc_idx]);
> +
> +       eqos->config->ops->eqos_inval_buffer(packet, length);
> +
>         rx_desc->des0 = (u32)(ulong)packet;
>         rx_desc->des1 = 0;
>         rx_desc->des2 = 0;
> @@ -1492,6 +1495,9 @@ static int eqos_probe_resources_core(struct udevice *dev)
>         }
>         debug("%s: rx_pkt=%p\n", __func__, eqos->rx_pkt);
>
> +       eqos->config->ops->eqos_inval_buffer(eqos->rx_dma_buf,
> +                       EQOS_MAX_PACKET_SIZE * EQOS_DESCRIPTORS_RX);
> +
>         debug("%s: OK\n", __func__);
>         return 0;
>
> --
> 2.25.1
>
Reviewed-by: Ramon Fried <rfried.dev at gmail.com>