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net: stmmac: Avoid DMA_CHAN_CONTROL write if no Split Header support

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commit f8e7dfd6fdabb831846ab1970a875746559d491b upstream.

The driver assumes that split headers can be enabled/disabled without
stopping/starting the device, so it writes DMA_CHAN_CONTROL from
stmmac_set_features().  However, on my system (IP v5.10a without Split
Header support), simply writing DMA_CHAN_CONTROL when DMA is running
(for example, with the commands below) leads to a TX watchdog timeout.

 host$ socat TCP-LISTEN:1024,fork,reuseaddr - &
 device$ ethtool -K eth0 tso off
 device$ ethtool -K eth0 tso on
 device$ dd if=/dev/zero bs=1M count=10 | socat - TCP4:host:1024
 <tx watchdog timeout>

Note that since my IP is configured without Split Header support, the
driver always just reads and writes the same value to the
DMA_CHAN_CONTROL register.

I don't have access to any platforms with Split Header support so I
don't know if these writes to the DMA_CHAN_CONTROL while DMA is running
actually work properly on such systems.  I could not find anything in
the databook that says that DMA_CHAN_CONTROL should not be written when
the DMA is running.

But on systems without Split Header support, there is in any case no
need to call enable_sph() in stmmac_set_features() at all since SPH can
never be toggled, so we can avoid the watchdog timeout there by skipping
this call.

Fixes: 8c6fc097a2f4acf ("net: stmmac: gmac4+: Add Split Header support")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vincent Whitchurch 2021-11-26 16:51:15 +01:00 committed by Greg Kroah-Hartman
parent a927f9dfd0
commit 823ae758c0
1 changed files with 6 additions and 5 deletions
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11
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
View File

@ -5531,8 +5531,6 @@ static int stmmac_set_features(struct net_device *netdev,
netdev_features_t features)
{
struct stmmac_priv *priv = netdev_priv(netdev);
bool sph_en;
u32 chan;
/* Keep the COE Type in case of csum is supporting */
if (features & NETIF_F_RXCSUM)
@ -5544,10 +5542,13 @@ static int stmmac_set_features(struct net_device *netdev,
*/
stmmac_rx_ipc(priv, priv->hw);
sph_en = (priv->hw->rx_csum > 0) && priv->sph;
if (priv->sph_cap) {
bool sph_en = (priv->hw->rx_csum > 0) && priv->sph;
u32 chan;
for (chan = 0; chan < priv->plat->rx_queues_to_use; chan++)
stmmac_enable_sph(priv, priv->ioaddr, sph_en, chan);
for (chan = 0; chan < priv->plat->rx_queues_to_use; chan++)
stmmac_enable_sph(priv, priv->ioaddr, sph_en, chan);
}
return 0;
}