On 11/28/2016 02:38 AM, Sebastian Frias wrote: > On 27/11/16 19:44, Florian Fainelli wrote: >> 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. >> >> Signed-off-by: Florian Fainelli <f.faine...@gmail.com> >> --- >> Documentation/networking/phy.txt | 18 ++++++++++++++++-- >> 1 file 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() > > If the bits are set after phy_connect(), how does the PHY framework knows > there's > an update to the bits? Should some call be made?
You would most likely either call phy_start() to start the PHY state machine (again) or have to re-negotiate the link with e.g: genphy_restart_aneg(). -- Florian
