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Message-ID: <20231013154800.GQ29570@kernel.org>
Date: Fri, 13 Oct 2023 17:48:00 +0200
From: Simon Horman <horms@...nel.org>
To: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: Woojung Huh <woojung.huh@...rochip.com>,
UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Heiner Kallweit <hkallweit1@...il.com>, kernel@...gutronix.de,
linux-kernel@...r.kernel.org, Russell King <linux@...linux.org.uk>,
netdev@...r.kernel.org
Subject: Re: [PATCH net-next v1 3/3] net: phy: micrel: Fix forced link mode
for KSZ886X switches
On Wed, Oct 11, 2023 at 02:38:56PM +0200, Oleksij Rempel wrote:
> Address a link speed detection issue in KSZ886X PHY driver when in
> forced link mode. Previously, link partners like "ASIX AX88772B"
> with KSZ8873 could fall back to 10Mbit instead of configured 100Mbit.
>
> The issue arises as KSZ886X PHY continues sending Fast Link Pulses (FLPs)
> even with autonegotiation off, misleading link partners in autoneg mode,
> leading to incorrect link speed detection.
>
> Now, when autonegotiation is disabled, the driver sets the link state
> forcefully using KSZ886X_CTRL_FORCE_LINK bit. This action, beyond just
> disabling autonegotiation, makes the PHY state more reliably detected by
> link partners using parallel detection, thus fixing the link speed
> misconfiguration.
>
> With autonegotiation enabled, link state is not forced, allowing proper
> autonegotiation process participation.
>
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
> drivers/net/phy/micrel.c | 32 +++++++++++++++++++++++++++++---
> 1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index 927d3d54658e..12f093aed4ff 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -1729,9 +1729,35 @@ static int ksz886x_config_aneg(struct phy_device *phydev)
> {
> int ret;
>
> - ret = genphy_config_aneg(phydev);
> - if (ret)
> - return ret;
> + if (phydev->autoneg != AUTONEG_ENABLE) {
> + ret = genphy_setup_forced(phydev);
> + if (ret)
> + return ret;
> +
> + /* When autonegotation is disabled, we need to manually force
nit: autonegotiation
> + * the link state. If we don't do this, the PHY will keep
> + * sending Fast Link Pulses (FLPs) which are part of the
> + * autonegotiation process. This is not desired when
> + * autonegotiation is off.
> + */
...
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