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cpu/stm32: Fix reception bug in periph_eth

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The reception code hands RX DMA descriptors back to the DMA right after its
contents were copied into the network stack internal buffer. This increases
the odds that the DMA never runs out of DMA descriptors to fill, even under
high load. However, the loop fetching the Ethernet frame stops to iterate at the
end of the frame. If the DMA used one more descriptor to store the FCS, this
was not returned back to the DMA. This commit fixes it.
This commit is contained in:
Marian Buschsieweke 2020-10-27 21:19:54 +01:00
parent 7ced6a8ac8
commit 45dc86acce
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GPG Key ID: 61F64C6599B1539F
1 changed files with 7 additions and 0 deletions
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cpu/stm32/periph/eth.c
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@ -652,6 +652,13 @@ static int stm32_eth_recv(netdev_t *netdev, void *buf, size_t max_len,
rx_curr = rx_curr->desc_next;
}
if ((size + ETHERNET_FCS_LEN - 1) % ETH_RX_BUFFER_SIZE < ETHERNET_FCS_LEN) {
/* one additional rx descriptor was needed only for the FCS, hand that
* back to the DMA as well */
rx_curr->status = RX_DESC_STAT_OWN;
rx_curr = rx_curr->desc_next;
}
_debug_rx_descriptor_info(__LINE__);
handle_lost_rx_irqs();
return size;