| Message ID | 20211126155115.12394-1-vincent.whitchurch@axis.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f8e7dfd6fdabb831846ab1970a875746559d491b |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: stmmac: Avoid DMA_CHAN_CONTROL write if no Split Header support | expand |
Hello: This patch was applied to netdev/net.git (master) by David S. Miller <davem@davemloft.net>: On Fri, 26 Nov 2021 16:51:15 +0100 you wrote: > 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> > > [...] Here is the summary with links: - [net] net: stmmac: Avoid DMA_CHAN_CONTROL write if no Split Header support https://git.kernel.org/netdev/net/c/f8e7dfd6fdab You are awesome, thank you!
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 2eb284576336..0ee513f67677 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -5504,8 +5504,6 @@ 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) @@ -5517,10 +5515,13 @@ 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; }
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> --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)