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Message-Id: <20221012134558.79737-1-saproj@gmail.com>
Date: Wed, 12 Oct 2022 16:45:58 +0300
From: Sergei Antonov <saproj@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, Sergei Antonov <saproj@...il.com>
Subject: [PATCH net] net: ftmac100: do not reject packets bigger than 1514
Dispite datasheet [1] saying the controller should allow incoming
packets of length >=1518, it only allows packets of length <=1514.
Since 1518 is a standard Ethernet maximum frame size, and it can
easily be encountered (in SSH for example), fix this behaviour:
* Set FTMAC100_MACCR_RX_FTL in the MAC Control Register.
* Check for packet size > 1518 in ftmac100_rx_packet_error().
[1]
https://bitbucket.org/Kasreyn/mkrom-uc7112lx/src/master/documents/FIC8120_DS_v1.2.pdf
Fixes: 8d77c036b57c ("net: add Faraday FTMAC100 10/100 Ethernet driver")
Signed-off-by: Sergei Antonov <saproj@...il.com>
---
drivers/net/ethernet/faraday/ftmac100.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/faraday/ftmac100.c b/drivers/net/ethernet/faraday/ftmac100.c
index d95d78230828..34d0284079ff 100644
--- a/drivers/net/ethernet/faraday/ftmac100.c
+++ b/drivers/net/ethernet/faraday/ftmac100.c
@@ -154,6 +154,7 @@ static void ftmac100_set_mac(struct ftmac100 *priv, const unsigned char *mac)
FTMAC100_MACCR_CRC_APD | \
FTMAC100_MACCR_FULLDUP | \
FTMAC100_MACCR_RX_RUNT | \
+ FTMAC100_MACCR_RX_FTL | \
FTMAC100_MACCR_RX_BROADPKT)
static int ftmac100_start_hw(struct ftmac100 *priv)
@@ -320,6 +321,7 @@ static bool ftmac100_rx_packet_error(struct ftmac100 *priv,
{
struct net_device *netdev = priv->netdev;
bool error = false;
+ const unsigned int length = ftmac100_rxdes_frame_length(rxdes);
if (unlikely(ftmac100_rxdes_rx_error(rxdes))) {
if (net_ratelimit())
@@ -337,9 +339,16 @@ static bool ftmac100_rx_packet_error(struct ftmac100 *priv,
error = true;
}
- if (unlikely(ftmac100_rxdes_frame_too_long(rxdes))) {
+ /* The frame-too-long flag 'FTMAC100_RXDES0_FTL' is described in the
+ * datasheet as: "When set, it indicates that the received packet
+ * length exceeds 1518 bytes." But testing shows that it is also set
+ * when packet length is equal to 1518.
+ * Since 1518 is a standard Ethernet maximum frame size, let it pass
+ * and only trigger an error when packet length really exceeds it.
+ */
+ if (unlikely(ftmac100_rxdes_frame_too_long(rxdes) && length > 1518)) {
if (net_ratelimit())
- netdev_info(netdev, "rx frame too long\n");
+ netdev_info(netdev, "rx frame too long (%u)\n", length);
netdev->stats.rx_length_errors++;
error = true;
--
2.34.1
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