Re: [PATCH net v2] net: ethernet: ti: cpsw: fix min eth packet size for non-switch use-cases

On 05/08/2021 17:55, Grygorii Strashko wrote:

The CPSW switchdev driver inherited fix from commit 9421c9015047 ("net: ethernet: ti: cpsw: fix min eth packet size") which changes min TX packet size to 64bytes (VLAN_ETH_ZLEN, excluding ETH_FCS). It was done to fix HW packed drop issue when packets are sent from Host to the port with PVID and un-tagging enabled. Unfortunately this breaks some other non-switch specific use-cases, like:

• [1] CPSW port as DSA CPU port with DSA-tag applied at the end of the

packet

• [2] Some industrial protocols, which expects min TX packet size 60Bytes

(excluding FCS).

Fix it by configuring min TX packet size depending on driver mode

• 60Bytes (ETH_ZLEN) for multi mac (dual-mac) mode
• 64Bytes (VLAN_ETH_ZLEN) for switch mode

and update it during driver mode change and annotate with READ_ONCE()/WRITE_ONCE() as it can be read by napi while writing.

[1] https://lore.kernel.org/netdev/20210531124051.GA15218@cephalopod/ [2] https://e2e.ti.com/support/arm/sitara_arm/f/791/t/701669

Cc: stable@vger.kernel.org Fixes: ed3525eda4c4 ("net: ethernet: ti: introduce cpsw switchdev based driver part 1 - dual-emac") Reported-by: Ben Hutchings ben.hutchings@essensium.com Signed-off-by: Grygorii Strashko grygorii.strashko@ti.com

---

Changes in v2:

• use skb_put_padto
• update description
• annotate tx_packet_min with READ_ONCE()/WRITE_ONCE()

I'm not going to add additional changes in cpdma configuration interface and, instead, will send patches to convert all cpdma users to use skb_put_padto() and drop frames padding from cpdma.

v1: https://patchwork.kernel.org/project/netdevbpf/patch/20210611132732.10690-1-...

drivers/net/ethernet/ti/cpsw_new.c | 7 +++++-- drivers/net/ethernet/ti/cpsw_priv.h | 4 +++- 2 files changed, 8 insertions(+), 3 deletions(-)

Cc: Ilias Apalodimas ilias.apalodimas@linaro.org

diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c index ae167223e87f..d904f4ca4b37 100644 --- a/drivers/net/ethernet/ti/cpsw_new.c +++ b/drivers/net/ethernet/ti/cpsw_new.c @@ -921,7 +921,7 @@ static netdev_tx_t cpsw_ndo_start_xmit(struct sk_buff *skb, struct cpdma_chan *txch; int ret, q_idx;

• if (skb_padto(skb, CPSW_MIN_PACKET_SIZE)) {

• if (skb_put_padto(skb, READ_ONCE(priv->tx_packet_min))) { cpsw_err(priv, tx_err, "packet pad failed\n"); ndev->stats.tx_dropped++; return NET_XMIT_DROP;

@@ -1101,7 +1101,7 @@ static int cpsw_ndo_xdp_xmit(struct net_device *ndev, int n, for (i = 0; i < n; i++) { xdpf = frames[i];

• if (xdpf->len < CPSW_MIN_PACKET_SIZE)
  

• if (xdpf->len < READ_ONCE(priv->tx_packet_min))
  break;
  

if (cpsw_xdp_tx_frame(priv, xdpf, NULL, priv->emac_port)) @@ -1390,6 +1390,7 @@ static int cpsw_create_ports(struct cpsw_common *cpsw) priv->dev = dev; priv->msg_enable = netif_msg_init(debug_level, CPSW_DEBUG); priv->emac_port = i + 1;

• priv->tx_packet_min = CPSW_MIN_PACKET_SIZE;
  

if (is_valid_ether_addr(slave_data->mac_addr)) { ether_addr_copy(priv->mac_addr, slave_data->mac_addr); @@ -1698,6 +1699,7 @@ static int cpsw_dl_switch_mode_set(struct devlink *dl, u32 id, priv = netdev_priv(sl_ndev); slave->port_vlan = vlan;

• 	WRITE_ONCE(priv->tx_packet_min, CPSW_MIN_PACKET_SIZE_VLAN);
  if (netif_running(sl_ndev))
  	cpsw_port_add_switch_def_ale_entries(priv,
  					     slave);
  

@@ -1726,6 +1728,7 @@ static int cpsw_dl_switch_mode_set(struct devlink *dl, u32 id, priv = netdev_priv(slave->ndev); slave->port_vlan = slave->data->dual_emac_res_vlan;

• 	WRITE_ONCE(priv->tx_packet_min, CPSW_MIN_PACKET_SIZE);
  cpsw_port_add_dual_emac_def_ale_entries(priv, slave);
  

  }

diff --git a/drivers/net/ethernet/ti/cpsw_priv.h b/drivers/net/ethernet/ti/cpsw_priv.h index a323bea54faa..2951fb7b9dae 100644 --- a/drivers/net/ethernet/ti/cpsw_priv.h +++ b/drivers/net/ethernet/ti/cpsw_priv.h @@ -89,7 +89,8 @@ do { \ #define CPSW_POLL_WEIGHT 64 #define CPSW_RX_VLAN_ENCAP_HDR_SIZE 4 -#define CPSW_MIN_PACKET_SIZE (VLAN_ETH_ZLEN) +#define CPSW_MIN_PACKET_SIZE_VLAN (VLAN_ETH_ZLEN) +#define CPSW_MIN_PACKET_SIZE (ETH_ZLEN) #define CPSW_MAX_PACKET_SIZE (VLAN_ETH_FRAME_LEN +\ ETH_FCS_LEN +\ CPSW_RX_VLAN_ENCAP_HDR_SIZE) @@ -380,6 +381,7 @@ struct cpsw_priv { u32 emac_port; struct cpsw_common *cpsw; int offload_fwd_mark;

• u32 tx_packet_min; };

#define ndev_to_cpsw(ndev) (((struct cpsw_priv *)netdev_priv(ndev))->cpsw)