Messages in this thread | | | Date | Wed, 30 Aug 2023 13:51:51 +0200 | From | Lukasz Majewski <> | Subject | Re: [PATCH 2/2] net: phy: Provide Module 4 KSZ9477 errata (DS80000754C) |
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Hi Oleksij,
> On Wed, Aug 30, 2023 at 12:52:24PM +0200, Lukasz Majewski wrote: > > Hi Oleksij, > > > > > On Wed, Aug 30, 2023 at 11:21:19AM +0200, Lukasz Majewski wrote: > > > > The KSZ9477 errata points out (in 'Module 4') the link up/down > > > > problem when EEE (Energy Efficient Ethernet) is enabled in the > > > > device to which the KSZ9477 tries to auto negotiate. > > > > > > > > The suggested workaround is to clear advertisement of EEE for > > > > PHYs in this chip driver. > > > > > > > > Signed-off-by: Lukasz Majewski <lukma@denx.de> > > > > --- > > > > drivers/net/phy/micrel.c | 31 ++++++++++++++++++++++++++++++- > > > > 1 file changed, 30 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c > > > > index 87b090ad2874..469dcd8a5711 100644 > > > > --- a/drivers/net/phy/micrel.c > > > > +++ b/drivers/net/phy/micrel.c > > > > @@ -1418,6 +1418,35 @@ static int ksz9131_get_features(struct > > > > phy_device *phydev) return 0; > > > > } > > > > > > > > +static int ksz9477_get_features(struct phy_device *phydev) > > > > +{ > > > > + __ETHTOOL_DECLARE_LINK_MODE_MASK(zero) = { 0, }; > > > > + int ret; > > > > + > > > > + ret = genphy_read_abilities(phydev); > > > > + if (ret) > > > > + return ret; > > > > + > > > > + /* KSZ9477 Errata DS80000754C > > > > + * > > > > + * Module 4: Energy Efficient Ethernet (EEE) feature > > > > select must be > > > > + * manually disabled > > > > + * The EEE feature is enabled by default, but it is > > > > not fully > > > > + * operational. It must be manually disabled through > > > > register > > > > + * controls. If not disabled, the PHY ports can > > > > auto-negotiate > > > > + * to enable EEE, and this feature can cause link > > > > drops when linked > > > > + * to another device supporting EEE. > > > > + * > > > > + * Although, the KSZ9477 MMD register > > > > + * (MMD_DEVICE_ID_EEE_ADV.MMD_EEE_ADV) advertise that > > > > EEE is > > > > + * operational one needs to manualy clear them to > > > > follow the chip > > > > + * errata. > > > > + */ > > > > + linkmode_and(phydev->supported_eee, phydev->supported, > > > > zero); + > > > > + return 0; > > > > +} > > > > + > > > > #define KSZ8873MLL_GLOBAL_CONTROL_4 0x06 > > > > #define KSZ8873MLL_GLOBAL_CONTROL_4_DUPLEX BIT(6) > > > > #define KSZ8873MLL_GLOBAL_CONTROL_4_SPEED BIT(4) > > > > @@ -4871,7 +4900,7 @@ static struct phy_driver ksphy_driver[] = > > > > { .handle_interrupt = kszphy_handle_interrupt, > > > > .suspend = genphy_suspend, > > > > .resume = genphy_resume, > > > > - .get_features = ksz9131_get_features, > > > > + .get_features = ksz9477_get_features, > > > > > > Sorry, i didn't described all details how to implement it. > > > > > > This code will break EEE support for the KSZ8563R switch. > > > > > > > And then another switch (KSZ8563R) pops up.... with regression.... > > Initially ksz9477_get_features() was introduced to fix KSZ8563R. > > > In the micrel.c the ksz9477_get_features was only present in: > > https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/micrel.c#L4832 > > https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/micrel.c#L4874 > > so I only changed it there. > > > > Apparently the KSZ8563R re-uses the KSZ9477 code. > > Most (all?) switch variant support by the ksz9477 DSA driver share > the same PHYid, so it is not possible to identify it by the micrel.c > PHY driver. As far as a know, the only commonly accepted way to > notify about some quirks between this both drivers is not user > dev_flags. >
We would need another idea on fixing this problem as there is following order of function calls:
-> ksz9477_setup -> ksz9477_get_features (here we are supposed to use the MICREL_NO_EEE flag) -> ksz_get_phy_flags (here we are supposed to set the MICREL_NO_EEE flag)
The ksz9477_get_features is called early.
It looks like the most optimal solution would be the one proposed by Tristam: https://www.spinics.net/lists/netdev/msg932044.html
It would clear the 7.60 per-port register with two ksz_write16 functions.
That exactly follows the recommendation for KSZ9477 Errata Module4.
> Regards, > Oleskij
Best regards,
Lukasz Majewski
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