[PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[Raju Rangoju]

During interface toggle operations (ifdown/ifup), the driver currently
resets the local helper variable 'phy_link' to -1. This causes the link
state machine to incorrectly interpret the state as a link change event,
resulting in spurious "Link is down" messages being logged when the
interface is brought back up.

Preserve the phy_link state across interface toggles to avoid treating
the -1 sentinel value as a legitimate link state transition.

Fixes: 88131a812b16 ("amd-xgbe: Perform phy connect/disconnect at dev open/stop")
Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c  | 1 -
 drivers/net/ethernet/amd/xgbe/xgbe-mdio.c | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index f0989aa01855..4dc631af7933 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -1080,7 +1080,6 @@ static void xgbe_free_rx_data(struct xgbe_prv_data *pdata)
 
 static int xgbe_phy_reset(struct xgbe_prv_data *pdata)
 {
-	pdata->phy_link = -1;
 	pdata->phy_speed = SPEED_UNKNOWN;
 
 	return pdata->phy_if.phy_reset(pdata);
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
index 1a37ec45e650..7675bb98f029 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
@@ -1555,6 +1555,7 @@ static int xgbe_phy_init(struct xgbe_prv_data *pdata)
 		pdata->phy.duplex = DUPLEX_FULL;
 	}
 
+	pdata->phy_link = 0;
 	pdata->phy.link = 0;
 
 	pdata->phy.pause_autoneg = pdata->pause_autoneg;
-- 
2.34.1

Re: [PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[Dawid Osuchowski]

On 2025-10-10 8:51 AM, Raju Rangoju wrote:
> During interface toggle operations (ifdown/ifup), the driver currently
> resets the local helper variable 'phy_link' to -1. This causes the link
> state machine to incorrectly interpret the state as a link change event,
> resulting in spurious "Link is down" messages being logged when the
> interface is brought back up.
> 
> Preserve the phy_link state across interface toggles to avoid treating
> the -1 sentinel value as a legitimate link state transition.
> 
> Fixes: 88131a812b16 ("amd-xgbe: Perform phy connect/disconnect at dev open/stop")
> Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>

Reviewed-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>
> ---
>   drivers/net/ethernet/amd/xgbe/xgbe-drv.c  | 1 -
>   drivers/net/ethernet/amd/xgbe/xgbe-mdio.c | 1 +
>   2 files changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> index f0989aa01855..4dc631af7933 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> @@ -1080,7 +1080,6 @@ static void xgbe_free_rx_data(struct xgbe_prv_data *pdata)
>   
>   static int xgbe_phy_reset(struct xgbe_prv_data *pdata)
>   {
> -	pdata->phy_link = -1;
>   	pdata->phy_speed = SPEED_UNKNOWN;
>   
>   	return pdata->phy_if.phy_reset(pdata);
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> index 1a37ec45e650..7675bb98f029 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> @@ -1555,6 +1555,7 @@ static int xgbe_phy_init(struct xgbe_prv_data *pdata)
>   		pdata->phy.duplex = DUPLEX_FULL;
>   	}
>   
> +	pdata->phy_link = 0;
>   	pdata->phy.link = 0;

Took me a sec to spot the difference between the two :)

>   
>   	pdata->phy.pause_autoneg = pdata->pause_autoneg;

Re: [PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[Tom Lendacky]

On 10/10/25 01:51, Raju Rangoju wrote:
> During interface toggle operations (ifdown/ifup), the driver currently
> resets the local helper variable 'phy_link' to -1. This causes the link
> state machine to incorrectly interpret the state as a link change event,
> resulting in spurious "Link is down" messages being logged when the
> interface is brought back up.
> 
> Preserve the phy_link state across interface toggles to avoid treating
> the -1 sentinel value as a legitimate link state transition.
> 
> Fixes: 88131a812b16 ("amd-xgbe: Perform phy connect/disconnect at dev open/stop")

Did this always happen, that is, did this behavior exist before the recent
changes to detect short drops in the phy link status? If it didn't exist
prior to those changes, then the Fixes: needs to be against that recent
change, possibly limiting the amount of backporting required into stable
kernels.

Thanks,
Tom

> Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
> ---
>  drivers/net/ethernet/amd/xgbe/xgbe-drv.c  | 1 -
>  drivers/net/ethernet/amd/xgbe/xgbe-mdio.c | 1 +
>  2 files changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> index f0989aa01855..4dc631af7933 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
> @@ -1080,7 +1080,6 @@ static void xgbe_free_rx_data(struct xgbe_prv_data *pdata)
>  
>  static int xgbe_phy_reset(struct xgbe_prv_data *pdata)
>  {
> -	pdata->phy_link = -1;
>  	pdata->phy_speed = SPEED_UNKNOWN;
>  
>  	return pdata->phy_if.phy_reset(pdata);
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> index 1a37ec45e650..7675bb98f029 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
> @@ -1555,6 +1555,7 @@ static int xgbe_phy_init(struct xgbe_prv_data *pdata)
>  		pdata->phy.duplex = DUPLEX_FULL;
>  	}
>  
> +	pdata->phy_link = 0;
>  	pdata->phy.link = 0;
>  
>  	pdata->phy.pause_autoneg = pdata->pause_autoneg;

Re: [PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[Rangoju, Raju]

On 10/10/2025 7:00 PM, Tom Lendacky wrote:
> On 10/10/25 01:51, Raju Rangoju wrote:
>> During interface toggle operations (ifdown/ifup), the driver currently
>> resets the local helper variable 'phy_link' to -1. This causes the link
>> state machine to incorrectly interpret the state as a link change event,
>> resulting in spurious "Link is down" messages being logged when the
>> interface is brought back up.
>>
>> Preserve the phy_link state across interface toggles to avoid treating
>> the -1 sentinel value as a legitimate link state transition.
>>
>> Fixes: 88131a812b16 ("amd-xgbe: Perform phy connect/disconnect at dev open/stop")
> 
> Did this always happen, that is, did this behavior exist before the recent
> changes to detect short drops in the phy link status? 

Yes, this behavior exist before the recent changes to detect short drops.

> If it didn't exist
> prior to those changes, then the Fixes: needs to be against that recent
> change, possibly limiting the amount of backporting required into stable
> kernels.
> 
> Thanks,
> Tom
> 
>> Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
>> ---
>>   drivers/net/ethernet/amd/xgbe/xgbe-drv.c  | 1 -
>>   drivers/net/ethernet/amd/xgbe/xgbe-mdio.c | 1 +
>>   2 files changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
>> index f0989aa01855..4dc631af7933 100644
>> --- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
>> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
>> @@ -1080,7 +1080,6 @@ static void xgbe_free_rx_data(struct xgbe_prv_data *pdata)
>>   
>>   static int xgbe_phy_reset(struct xgbe_prv_data *pdata)
>>   {
>> -	pdata->phy_link = -1;
>>   	pdata->phy_speed = SPEED_UNKNOWN;
>>   
>>   	return pdata->phy_if.phy_reset(pdata);
>> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
>> index 1a37ec45e650..7675bb98f029 100644
>> --- a/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
>> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-mdio.c
>> @@ -1555,6 +1555,7 @@ static int xgbe_phy_init(struct xgbe_prv_data *pdata)
>>   		pdata->phy.duplex = DUPLEX_FULL;
>>   	}
>>   
>> +	pdata->phy_link = 0;
>>   	pdata->phy.link = 0;
>>   
>>   	pdata->phy.pause_autoneg = pdata->pause_autoneg;
> 

Re: [PATCH net] amd-xgbe: Avoid spurious link down messages during interface toggle

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Fri, 10 Oct 2025 12:21:42 +0530 you wrote:
> During interface toggle operations (ifdown/ifup), the driver currently
> resets the local helper variable 'phy_link' to -1. This causes the link
> state machine to incorrectly interpret the state as a link change event,
> resulting in spurious "Link is down" messages being logged when the
> interface is brought back up.
> 
> Preserve the phy_link state across interface toggles to avoid treating
> the -1 sentinel value as a legitimate link state transition.
> 
> [...]

Here is the summary with links:
  - [net] amd-xgbe: Avoid spurious link down messages during interface toggle
    https://git.kernel.org/netdev/net/c/2616222e4233

You are awesome, thank you!
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