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Diffstat (limited to 'Documentation/networking/phy.rst')
| -rw-r--r-- | Documentation/networking/phy.rst | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/Documentation/networking/phy.rst b/Documentation/networking/phy.rst index 0dd90d7df5ec..a689966bc4be 100644 --- a/Documentation/networking/phy.rst +++ b/Documentation/networking/phy.rst @@ -202,7 +202,8 @@ the PHY/controller, of which the PHY needs to be aware. *interface* is a u32 which specifies the connection type used between the controller and the PHY. Examples are GMII, MII, -RGMII, and SGMII. For a full list, see include/linux/phy.h +RGMII, and SGMII. See "PHY interface mode" below. For a full +list, see include/linux/phy.h Now just make sure that phydev->supported and phydev->advertising have any values pruned from them which don't make sense for your controller (a 10/100 @@ -225,6 +226,48 @@ When you want to disconnect from the network (even if just briefly), you call phy_stop(phydev). This function also stops the phylib state machine and disables PHY interrupts. +PHY interface modes +=================== + +The PHY interface mode supplied in the phy_connect() family of functions +defines the initial operating mode of the PHY interface. This is not +guaranteed to remain constant; there are PHYs which dynamically change +their interface mode without software interaction depending on the +negotiation results. + +Some of the interface modes are described below: + +``PHY_INTERFACE_MODE_1000BASEX`` + This defines the 1000BASE-X single-lane serdes link as defined by the + 802.3 standard section 36. The link operates at a fixed bit rate of + 1.25Gbaud using a 10B/8B encoding scheme, resulting in an underlying + data rate of 1Gbps. Embedded in the data stream is a 16-bit control + word which is used to negotiate the duplex and pause modes with the + remote end. This does not include "up-clocked" variants such as 2.5Gbps + speeds (see below.) + +``PHY_INTERFACE_MODE_2500BASEX`` + This defines a variant of 1000BASE-X which is clocked 2.5 times faster, + than the 802.3 standard giving a fixed bit rate of 3.125Gbaud. + +``PHY_INTERFACE_MODE_SGMII`` + This is used for Cisco SGMII, which is a modification of 1000BASE-X + as defined by the 802.3 standard. The SGMII link consists of a single + serdes lane running at a fixed bit rate of 1.25Gbaud with 10B/8B + encoding. The underlying data rate is 1Gbps, with the slower speeds of + 100Mbps and 10Mbps being achieved through replication of each data symbol. + The 802.3 control word is re-purposed to send the negotiated speed and + duplex information from to the MAC, and for the MAC to acknowledge + receipt. This does not include "up-clocked" variants such as 2.5Gbps + speeds. + + Note: mismatched SGMII vs 1000BASE-X configuration on a link can + successfully pass data in some circumstances, but the 16-bit control + word will not be correctly interpreted, which may cause mismatches in + duplex, pause or other settings. This is dependent on the MAC and/or + PHY behaviour. + + Pause frames / flow control =========================== |