Messages in this thread | | | Subject | Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on | From | Huazhong Tan <> | Date | Sat, 27 Feb 2021 09:27:54 +0800 |
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On 2021/2/27 8:53, Andrew Lunn wrote: > On Fri, Feb 26, 2021 at 03:44:42PM +0800, Huazhong Tan wrote: >> From: Guangbin Huang <huangguangbin2@huawei.com> >> >> If phy uses generic driver and autoneg is on, enter command >> "ethtool -s eth0 speed 50" will not change phy speed actually, but >> command "ethtool eth0" shows speed is 50Mb/s because phydev->speed >> has been set to 50 and no update later. >> >> And duplex setting has same problem too. >> >> However, if autoneg is on, phy only changes speed and duplex according to >> phydev->advertising, but not phydev->speed and phydev->duplex. So in this >> case, phydev->speed and phydev->duplex don't need to be set in function >> phy_ethtool_ksettings_set() if autoneg is on. >> >> Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com> >> Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com> > I'm not sure, but i think this happens after > > commit 51e2a3846eab18711f4eb59cd0a4c33054e2980a > Author: Trent Piepho <tpiepho@freescale.com> > Date: Wed Sep 24 10:55:46 2008 +0000 > > PHY: Avoid unnecessary aneg restarts > > The PHY's aneg is configured and restarted whenever the link is brought up, > e.g. when DHCP is started after the kernel has booted. This can take the > link down for several seconds while auto-negotiation is redone. > > If the advertised features haven't changed, then it shouldn't be necessary > to bring down the link and start auto-negotiation over again. > > genphy_config_advert() is enhanced to return 0 when the advertised features > haven't been changed and >0 when they have been. > > genphy_config_aneg() then uses this information to not call > genphy_restart_aneg() if there has been no change. > > Before then, i think autoneg was unconditionally restarted, and so the > speed would get overwritten when autoneg completed. After this patch, > since autoneg is not being changed when only speed is set, autoneg is > not triggered. > > Andrew
Thanks.
> .
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