[PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[Huazhong Tan]

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>
---
 drivers/net/phy/phy.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 1be07e4..fc2e7cb 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -276,14 +276,16 @@ int phy_ethtool_ksettings_set(struct phy_device *phydev,
 
 	phydev->autoneg = autoneg;
 
-	phydev->speed = speed;
+	if (autoneg == AUTONEG_DISABLE) {
+		phydev->speed = speed;
+		phydev->duplex = duplex;
+	}
 
 	linkmode_copy(phydev->advertising, advertising);
 
 	linkmode_mod_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
 			 phydev->advertising, autoneg == AUTONEG_ENABLE);
 
-	phydev->duplex = duplex;
 	phydev->master_slave_set = cmd->base.master_slave_cfg;
 	phydev->mdix_ctrl = cmd->base.eth_tp_mdix_ctrl;
 
-- 
2.7.4

Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[Jakub Kicinski]

On Fri, 26 Feb 2021 15:44:42 +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.

Can we get a Fixes tag for this one? How far back does this behavior
date?

Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[Huazhong Tan]

On 2021/2/27 7:56, Jakub Kicinski wrote:
> On Fri, 26 Feb 2021 15:44:42 +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.
> Can we get a Fixes tag for this one? How far back does this behavior
> date?
will add a fixes tag in V2, thanks.
> .

Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[Andrew Lunn]

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

Re: [PATCH net] net: phy: fix save wrong speed and duplex problem if autoneg is on

[Huazhong Tan]

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.


> .