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net: dwc_eth_qos: Prevent DMA from writing updated RX DMA descriptor

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The DMA may attempt to write a DMA descriptor in the ring while it is
being updated. By writing the DMA descriptor buffer address to 0, it
is assured the DMA will not use such a buffer and the buffer can be
updated without any interference.

Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: Ramon Fried <rfried.dev@gmail.com>
Cc: Stephen Warren <swarren@nvidia.com>
This commit is contained in:
Marek Vasut 2020-03-23 02:11:46 +01:00 committed by marex
parent a83ca0c280
commit 24891dd8d4
1 changed files with 3 additions and 1 deletions
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4
drivers/net/dwc_eth_qos.c
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@ -1477,8 +1477,10 @@ static int eqos_free_pkt(struct udevice *dev, uchar *packet, int length)
rx_desc = &(eqos->rx_descs[eqos->rx_desc_idx]);
rx_desc->des0 = 0;
mb();
eqos->config->ops->eqos_flush_desc(rx_desc);
eqos->config->ops->eqos_inval_buffer(packet, length);
rx_desc->des0 = (u32)(ulong)packet;
rx_desc->des1 = 0;
rx_desc->des2 = 0;