From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755114AbdC1KGk (ORCPT ); Tue, 28 Mar 2017 06:06:40 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:45184 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754533AbdC1KGc (ORCPT ); Tue, 28 Mar 2017 06:06:32 -0400 Subject: Re: [PATCH v3 1/2] net: phy: Fix PHY AN done state machine for interrupt driven PHYs To: , References: <1490180524-28675-1-git-send-email-rogerq@ti.com> <1490180524-28675-2-git-send-email-rogerq@ti.com> <078917ad-77a1-a722-1688-6203ae183a46@ti.com> CC: , , , , , "stable # v4 . 9+" , Sergei Shtylyov , "Andrew F. Davis" , "Nori, Sekhar" From: Roger Quadros Message-ID: Date: Tue, 28 Mar 2017 13:05:40 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <078917ad-77a1-a722-1688-6203ae183a46@ti.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +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 # v4.9+ > Signed-off-by: Roger Quadros > --- > 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