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authorFlorian Fainelli <f.fainelli@gmail.com>2016-11-28 05:45:13 +0300
committerDavid S. Miller <davem@davemloft.net>2016-11-29 00:07:42 +0300
commit2fa3e25b454e267d8f55ee19c27be540495463e7 (patch)
tree551af2ab98867240f91805588e163f197a464fed /Documentation/networking
parent527fd70e26e68d65a47e17e71f637dc42dbd26cc (diff)
downloadlinux-2fa3e25b454e267d8f55ee19c27be540495463e7.tar.xz
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: Martin Blumenstingl <martin.blumenstingl@googlemail.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/phy.txt18
1 files changed, 16 insertions, 2 deletions
diff --git a/Documentation/networking/phy.txt b/Documentation/networking/phy.txt
index 4b25c0f24201..9a42a9414cea 100644
--- a/Documentation/networking/phy.txt
+++ b/Documentation/networking/phy.txt
@@ -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