Re: [PATCH RFC net-next 6/6] net: dsa: sja1105: support switching between SGMII and 2500BASE-X
From: Vladimir Oltean <olteanv@gmail.com>
Date: 2022-02-25 11:16:56
On Thu, Feb 24, 2022 at 04:15:41PM +0000, Russell King (Oracle) wrote:
Vladimir Oltean suggests that sla1105 can support switching between
s/sla1105/sja1105/
quoted hunk ↗ jump to hunk
SGMII and 2500BASE-X modes. Augment sja1105_phylink_get_caps() to fill in both interface modes if they can be supported. Signed-off-by: Russell King (Oracle) <redacted> --- drivers/net/dsa/sja1105/sja1105_main.c | 28 +++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-)diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c index 5beef06d8ff7..36001b1d7968 100644 --- a/drivers/net/dsa/sja1105/sja1105_main.c +++ b/drivers/net/dsa/sja1105/sja1105_main.c@@ -1396,6 +1396,7 @@ static void sja1105_phylink_get_caps(struct dsa_switch *ds, int port, { struct sja1105_private *priv = ds->priv; struct sja1105_xmii_params_entry *mii; + phy_interface_t phy_mode; /* This driver does not make use of the speed, duplex, pause or the * advertisement in its mac_config, so it is safe to mark this driver@@ -1403,11 +1404,28 @@ static void sja1105_phylink_get_caps(struct dsa_switch *ds, int port, */ config->legacy_pre_march2020 = false; - /* The SJA1105 MAC programming model is through the static config - * (the xMII Mode table cannot be dynamically reconfigured), and - * we have to program that early. - */ - __set_bit(priv->phy_mode[port], config->supported_interfaces); + phy_mode = priv->phy_mode[port]; + if (phy_mode == PHY_INTERFACE_MODE_SGMII || + phy_mode == PHY_INTERFACE_MODE_2500BASEX) { + /* Changing the PHY mode on SERDES ports is possible and makes + * sense, because that is done through the XPCS. We allow + * changes between SGMII and 2500base-X (it is unknown whether + * 1000base-X is supported). + */
It is actually known (or so I think).
Bits 2:1 (PCS_MODE) of register VR_MII_AN_CTRL (MMD 0x1f, address 0x8001)
of the XPCS, as instantiated in SJA1105R/S, says:
00: Clause 37 auto-negotiation for 1000BASE-X mode
*Not supported*
10: Clause 37 auto-negotiation for SGMII mode
When I look at the XPCS documentation for SJA1110, it doesn't say
"Not supported", however I don't have the setup to try it.
If it's anything like the XPCS instantiation from SJA1105 though, this
is possibly a documentation glitch and I wouldn't say it was implemented
just because the documentation doesn't say it isn't.
On the other hand, disabling SGMII in-band autoneg is possible, and the
resulting mode is electrically compatible with 1000Base-X without
in-band autoneg. Interpret this as you wish.
+ if (priv->info->supports_sgmii[port])
+ __set_bit(PHY_INTERFACE_MODE_SGMII,
+ config->supported_interfaces);
+
+ if (priv->info->supports_2500basex[port])
+ __set_bit(PHY_INTERFACE_MODE_2500BASEX,
+ config->supported_interfaces);
+ } else {
+ /* The SJA1105 MAC programming model is through the static
+ * config (the xMII Mode table cannot be dynamically
+ * reconfigured), and we have to program that early.
+ */
+ __set_bit(phy_mode, config->supported_interfaces);
+ }
/* The MAC does not support pause frames, and also doesn't
* support half-duplex traffic modes.
--
2.30.2