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Date: Wed, 29 Jan 2020 13:06:22 +0100 From: Ivan Vecera <ivecera@...hat.com> To: Petr Oros <poros@...hat.com> Cc: netdev@...r.kernel.org, andrew@...n.ch, f.fainelli@...il.com, hkallweit1@...il.com Subject: Re: [PATCH net] phy: avoid unnecessary link-up delay in polling mode On Wed, 29 Jan 2020 11:13:08 +0100 Petr Oros <poros@...hat.com> wrote: > commit 93c0970493c71f ("net: phy: consider latched link-down status in > polling mode") removed double-read of latched link-state register for > polling mode from genphy_update_link(). This added extra ~1s delay into > sequence link down->up. > Following scenario: > - After boot link goes up > - phy_start() is called triggering an aneg restart, hence link goes > down and link-down info is latched. > - After aneg has finished link goes up. In phy_state_machine is checked > link state but it is latched "link is down". The state machine is > scheduled after one second and there is detected "link is up". This > extra delay can be avoided when we keep link-state register double read > in case when link was down previously. > > With this solution we don't miss a link-down event in polling mode and > link-up is faster. > > Fixes: 93c0970493c71f ("net: phy: consider latched link-down status in polling mode") > Signed-off-by: Petr Oros <poros@...hat.com> > --- > drivers/net/phy/phy-c45.c | 5 +++-- > drivers/net/phy/phy_device.c | 5 +++-- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c > index a1caeee1223617..bceb0dcdecbd61 100644 > --- a/drivers/net/phy/phy-c45.c > +++ b/drivers/net/phy/phy-c45.c > @@ -239,9 +239,10 @@ int genphy_c45_read_link(struct phy_device *phydev) > > /* The link state is latched low so that momentary link > * drops can be detected. Do not double-read the status > - * in polling mode to detect such short link drops. > + * in polling mode to detect such short link drops except > + * the link was already down. > */ > - if (!phy_polling_mode(phydev)) { > + if (!phy_polling_mode(phydev) || !phydev->link) { > val = phy_read_mmd(phydev, devad, MDIO_STAT1); > if (val < 0) > return val; > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c > index 6a5056e0ae7757..d5f4804c34d597 100644 > --- a/drivers/net/phy/phy_device.c > +++ b/drivers/net/phy/phy_device.c > @@ -1930,9 +1930,10 @@ int genphy_update_link(struct phy_device *phydev) > > /* The link state is latched low so that momentary link > * drops can be detected. Do not double-read the status > - * in polling mode to detect such short link drops. > + * in polling mode to detect such short link drops except > + * the link was already down. > */ > - if (!phy_polling_mode(phydev)) { > + if (!phy_polling_mode(pihydev) || !phydev->link) { ^ Please remove the extra 'i' ---- Thx, Ivan
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