+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().
cheers,
-roger