Hi, On 28/03/17 13:05, Roger Quadros wrote: > +Andrew Davis & Sekhar. > > Hi, > > Andrew Davis posted a few comments offline which I'm clarifying here. > > On 27/03/17 14:59, Roger Quadros wrote: >> The Ethernet link on an interrupt driven PHY was not coming up if the >> Ethernet cable was plugged before the Ethernet interface was brought up. >> >> The PHY state machine seems to be stuck from RUNNING to AN state >> with no new interrupts from the PHY. So it doesn't know when the >> PHY Auto-negotiation has been completed and doesn't transition to RUNNING >> state with ANEG done thus netif_carrier_on() is never called. >> >> NOTE: genphy_config_aneg() will not restart PHY Auto-negotiation of >> advertisement parameters didn't change. > > Is phy->config_aneg expected to *always* restart auto-negotiation even if > advertisement parameters didn't change? > If so then we'll need to fix genphy_config_aneg(). > >> >> Fix this by scheduling the PHY state machine in phy_start_aneg(). >> There is no way of knowing in phy.c whether auto-negotiation was >> restarted or not by the PHY driver so we just wait for the next >> poll/interrupt to update the PHY state machine. >> >> Fixes: 3c293f4e08b5 ("net: phy: Trigger state machine on state change and not polling.") >> Cc: stable <stable@xxxxxxxxxxxxxxx> # v4.9+ >> Signed-off-by: Roger Quadros <rogerq@xxxxxx> >> --- >> v3: Fix typo in commit message >> >> drivers/net/phy/phy.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c >> index 1be69d8..49dedf8 100644 >> --- a/drivers/net/phy/phy.c >> +++ b/drivers/net/phy/phy.c >> @@ -630,6 +630,10 @@ int phy_start_aneg(struct phy_device *phydev) >> >> out_unlock: >> mutex_unlock(&phydev->lock); >> + if (!err && phy_interrupt_is_valid(phydev)) >> + queue_delayed_work(system_power_efficient_wq, >> + &phydev->state_queue, HZ); >> + >> return err; >> } >> EXPORT_SYMBOL(phy_start_aneg); >> > > There is still room for optimization for interrupt driven PHYs as I still > see a delay of 1 second between "ifconfig ethx up" and link status coming up > if cable was already plugged in. In fact if Auto-negotiation was already completed > and not required to be restarted, the PHY state machine should have move from > AN to RUNNING instantly without expecting a PHY interrupt. > > How can we get rid of the unnecessary delay in the case where auto-negotiation > is not restarted? > Should we check for phy_aneg_done() immediately after issuing a phy_start_aneg() > in phy_state_machine() and switch from PHY_AN to PHY_RUNNING? > > This should avoid the need to re-schedule the state machine in phy_start_angeg(). Any comments on my questions? cheers, -roger