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Commit 2fa3e25b authored by Florian Fainelli's avatar Florian Fainelli Committed by David S. Miller
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Documentation: net: phy: Add a paragraph about pause frames/flow control 



Describe that the Ethernet MAC controller is ultimately responsible for
dealing with proper pause frames/flow control advertisement and
enabling, and that it is therefore allowed to have it change
phydev->supported/advertising with SUPPORTED_Pause and
SUPPORTED_AsymPause.

Reviewed-by: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 527fd70e

Documentation/networking/phy.txt

+16 −2
Original line number Diff line number Diff line
@@ -127,8 +127,9 @@ Letting the PHY Abstraction Layer do Everything 
 values pruned from them which don't make sense for your controller (a 10/100

 controller may be connected to a gigabit capable PHY, so you would need to

 mask off SUPPORTED_1000baseT*).  See include/linux/ethtool.h for definitions

 for these bitfields. Note that you should not SET any bits, or the PHY may

 get put into an unsupported state.

 for these bitfields. Note that you should not SET any bits, except the

 SUPPORTED_Pause and SUPPORTED_AsymPause bits (see below), or the PHY may get

 put into an unsupported state.



 Lastly, once the controller is ready to handle network traffic, you call

 phy_start(phydev).  This tells the PAL that you are ready, and configures the
@@ -139,6 +140,19 @@ Letting the PHY Abstraction Layer do Everything 
 When you want to disconnect from the network (even if just briefly), you call

 phy_stop(phydev).



Pause frames / flow control



 The PHY does not participate directly in flow control/pause frames except by

 making sure that the SUPPORTED_Pause and SUPPORTED_AsymPause bits are set in

 MII_ADVERTISE to indicate towards the link partner that the Ethernet MAC

 controller supports such a thing. Since flow control/pause frames generation

 involves the Ethernet MAC driver, it is recommended that this driver takes care

 of properly indicating advertisement and support for such features by setting

 the SUPPORTED_Pause and SUPPORTED_AsymPause bits accordingly. This can be done

 either before or after phy_connect() and/or as a result of implementing the

 ethtool::set_pauseparam feature.





Keeping Close Tabs on the PAL



 It is possible that the PAL's built-in state machine needs a little help to