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Date: Sat, 23 Nov 2019 22:48:31 +0200 From: Vladimir Oltean <olteanv@...il.com> To: Florian Fainelli <f.fainelli@...il.com> Cc: Andrew Lunn <andrew@...n.ch>, Vivien Didelot <vivien.didelot@...il.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <jakub.kicinski@...ronome.com>, netdev <netdev@...r.kernel.org> Subject: Re: [PATCH net-next 2/3] net: dsa: sja1105: Implement the port MTU callbacks On Sat, 23 Nov 2019 at 22:30, Florian Fainelli <f.fainelli@...il.com> wrote: > > > > On 11/23/2019 11:48 AM, Vladimir Oltean wrote: > > On this switch, the frame length enforcements are performed by the > > ingress policers. There are 2 types of those: regular L2 (also called > > best-effort) and Virtual Link policers (an ARINC664/AFDX concept for > > defining L2 streams with certain QoS abilities). To avoid future > > confusion, I prefer to call the reset reason "Best-effort policers", > > even though the VL policers are not yet supported. > > > > We also need to change the setup of the initial static config, such that > > DSA calls to .change_mtu (which are expensive) become no-ops and don't > > reset the switch 5 times. > > > > A driver-level decision is to unconditionally allow single VLAN-tagged > > traffic on all ports. The CPU port must accept an additional VLAN header > > for the DSA tag, which is again a driver-level decision. > > > > The policers actually count bytes not only from the SDU, but also from > > the Ethernet header and FCS, so those need to be accounted for as well. > > > > Signed-off-by: Vladimir Oltean <olteanv@...il.com> > > --- > > drivers/net/dsa/sja1105/sja1105.h | 1 + > > drivers/net/dsa/sja1105/sja1105_main.c | 48 +++++++++++++++++++++++--- > > 2 files changed, 45 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h > > index d801fc204d19..3a5c8acb6e2a 100644 > > --- a/drivers/net/dsa/sja1105/sja1105.h > > +++ b/drivers/net/dsa/sja1105/sja1105.h > > @@ -122,6 +122,7 @@ enum sja1105_reset_reason { > > SJA1105_RX_HWTSTAMPING, > > SJA1105_AGEING_TIME, > > SJA1105_SCHEDULING, > > + SJA1105_BEST_EFFORT_POLICING, > > }; > > > > int sja1105_static_config_reload(struct sja1105_private *priv, > > diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c > > index b60224c55244..3d55dd3c7e83 100644 > > --- a/drivers/net/dsa/sja1105/sja1105_main.c > > +++ b/drivers/net/dsa/sja1105/sja1105_main.c > > @@ -459,12 +459,12 @@ static int sja1105_init_general_params(struct sja1105_private *priv) > > #define SJA1105_RATE_MBPS(speed) (((speed) * 64000) / 1000) > > > > static void sja1105_setup_policer(struct sja1105_l2_policing_entry *policing, > > - int index) > > + int index, int mtu) > > { > > policing[index].sharindx = index; > > policing[index].smax = 65535; /* Burst size in bytes */ > > policing[index].rate = SJA1105_RATE_MBPS(1000); > > - policing[index].maxlen = ETH_FRAME_LEN + VLAN_HLEN + ETH_FCS_LEN; > > + policing[index].maxlen = mtu; > > policing[index].partition = 0; > > } > > > > @@ -496,12 +496,16 @@ static int sja1105_init_l2_policing(struct sja1105_private *priv) > > */ > > for (i = 0, k = 0; i < SJA1105_NUM_PORTS; i++) { > > int bcast = (SJA1105_NUM_PORTS * SJA1105_NUM_TC) + i; > > + int mtu = VLAN_ETH_FRAME_LEN + ETH_FCS_LEN; > > + > > + if (dsa_is_cpu_port(priv->ds, i)) > > + mtu += VLAN_HLEN; > > That really seems like a layering violation it so happens that you use > DSA_TAG_8021Q which is why you need VLAN_ETH_HLEN, but you should not > assume that from with your driver, even if this one is special on so > many counts. How about using use dsa_port(port)->tag_ops->overhead + > ETH_HLEN here? True here. > > > > for (j = 0; j < SJA1105_NUM_TC; j++, k++) > > - sja1105_setup_policer(policing, k); > > + sja1105_setup_policer(policing, k, mtu); > > > > /* Set up this port's policer for broadcast traffic */ > > - sja1105_setup_policer(policing, bcast); > > + sja1105_setup_policer(policing, bcast, mtu); > > } > > return 0; > > } > > @@ -1346,6 +1350,7 @@ static const char * const sja1105_reset_reasons[] = { > > [SJA1105_RX_HWTSTAMPING] = "RX timestamping", > > [SJA1105_AGEING_TIME] = "Ageing time", > > [SJA1105_SCHEDULING] = "Time-aware scheduling", > > + [SJA1105_BEST_EFFORT_POLICING] = "Best-effort policing", > > }; > > > > /* For situations where we need to change a setting at runtime that is only > > @@ -1886,6 +1891,39 @@ static int sja1105_set_ageing_time(struct dsa_switch *ds, > > return sja1105_static_config_reload(priv, SJA1105_AGEING_TIME); > > } > > > > +static int sja1105_change_mtu(struct dsa_switch *ds, int port, int new_mtu) > > +{ > > + int bcast = (SJA1105_NUM_PORTS * SJA1105_NUM_TC) + port; > > + struct sja1105_l2_policing_entry *policing; > > + struct sja1105_private *priv = ds->priv; > > + int tc; > > + > > + new_mtu += VLAN_ETH_HLEN + ETH_FCS_LEN; > > Likewise Not the same thing here. I wrote about this one in the commit message: "A driver-level decision is to unconditionally allow single VLAN-tagged traffic on all ports". How is this handled more correctly? > -- > Florian Thanks, -Vladimir
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