[PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[Justin Chen]

When the revised suspend/resume sequence was introduced this led to an edge
case where the TX is left disabled in the following sequence.

1. phy link is down, so UMAC is held in reset and then network interface
   is WoL enabled
2. Enter suspend, bcmgenet_wol_power_down_cfg() enables UMAC_RX since MAC
   is in SW_RESET
4. Enter resume, UMAC_RX is left enabled. Since we only enable UMAC_TX
   and UMAC_RX in SW_RESET. The UMAC_TX is never enabled again on link up.

Fixes: 254f3239dd07 ("net: bcmgenet: revise suspend/resume")
Fixes: 88f6c8bf1aae ("net: bcmgenet: keep MAC in reset until PHY is up")
Signed-off-by: Justin Chen <justin.chen@broadcom.com>
---
 drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
index 96d5d4f7f51f..984432952963 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
@@ -253,6 +253,17 @@ int bcmgenet_wol_power_up_cfg(struct bcmgenet_priv *priv,
 	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 	reg &= ~CMD_CRC_FWD;
 	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+
+	/*
+	 * Mirror wol_power_down_cfg(). If only UMAC_RX
+	 * is enabled, then we must place the UMAC back
+	 * into SW_RESET.
+	 */
+	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
+	if ((reg & CMD_RX_EN) && !(reg & CMD_TX_EN)) {
+		reg |= CMD_SW_RESET;
+		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
+	}
 	spin_unlock_bh(&priv->reg_lock);
 
 	/* Resume link status tracking */
-- 
2.34.1

Re: [PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - What hardware the change was tested on. For driver fixes please
   mention the device (and if relevant firmware version) used for
   testing, or say that the change was not tested on real hardware.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[Florian Fainelli]

On 9/29/26 12:22, Justin Chen wrote:
> When the revised suspend/resume sequence was introduced this led to an edge
> case where the TX is left disabled in the following sequence.
> 
> 1. phy link is down, so UMAC is held in reset and then network interface
>     is WoL enabled
> 2. Enter suspend, bcmgenet_wol_power_down_cfg() enables UMAC_RX since MAC
>     is in SW_RESET
> 4. Enter resume, UMAC_RX is left enabled. Since we only enable UMAC_TX
>     and UMAC_RX in SW_RESET. The UMAC_TX is never enabled again on link up.
> 
> Fixes: 254f3239dd07 ("net: bcmgenet: revise suspend/resume")
> Fixes: 88f6c8bf1aae ("net: bcmgenet: keep MAC in reset until PHY is up")
> Signed-off-by: Justin Chen <justin.chen@broadcom.com>

Excellent catch, thanks!

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian

Re: [PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[Nicolai Buchwitz]

Hi Justin

On 29.9.2026 21:22, Justin Chen wrote:
> When the revised suspend/resume sequence was introduced this led to an 
> edge
> case where the TX is left disabled in the following sequence.
> 
> 1. phy link is down, so UMAC is held in reset and then network 
> interface
>    is WoL enabled
> 2. Enter suspend, bcmgenet_wol_power_down_cfg() enables UMAC_RX since 
> MAC
>    is in SW_RESET
> 4. Enter resume, UMAC_RX is left enabled. Since we only enable UMAC_TX
>    and UMAC_RX in SW_RESET. The UMAC_TX is never enabled again on link 
> up.
> 
> Fixes: 254f3239dd07 ("net: bcmgenet: revise suspend/resume")
> Fixes: 88f6c8bf1aae ("net: bcmgenet: keep MAC in reset until PHY is 
> up")

AFAIU before 254f3239dd07 resume always went through init_umac(), so 
older
kernels shouldn't be affected. If we drop the tag for, it would save 
some
backports to the older LTS kernels.

> Signed-off-by: Justin Chen <justin.chen@broadcom.com>
> ---
>  drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c 
> b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
> index 96d5d4f7f51f..984432952963 100644
> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
> @@ -253,6 +253,17 @@ int bcmgenet_wol_power_up_cfg(struct bcmgenet_priv 
> *priv,
>  	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
>  	reg &= ~CMD_CRC_FWD;
>  	bcmgenet_umac_writel(priv, reg, UMAC_CMD);
> +
> +	/*
> +	 * Mirror wol_power_down_cfg(). If only UMAC_RX
> +	 * is enabled, then we must place the UMAC back
> +	 * into SW_RESET.
> +	 */
> +	reg = bcmgenet_umac_readl(priv, UMAC_CMD);
> +	if ((reg & CMD_RX_EN) && !(reg & CMD_TX_EN)) {
> +		reg |= CMD_SW_RESET;
> +		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
> +	}
>  	spin_unlock_bh(&priv->reg_lock);
> 
>  	/* Resume link status tracking */

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>

Thanks,
Nicolai

Re: [PATCH net] net: bcmgenet: if UMAC was suspended in SW_RESET, restore it to SW_RESET

[Justin Chen]

On 9/29/26 2:09 PM, Nicolai Buchwitz wrote:
> Hi Justin
> 
> On 29.9.2026 21:22, Justin Chen wrote:
>> When the revised suspend/resume sequence was introduced this led to an 
>> edge
>> case where the TX is left disabled in the following sequence.
>>
>> 1. phy link is down, so UMAC is held in reset and then network interface
>>    is WoL enabled
>> 2. Enter suspend, bcmgenet_wol_power_down_cfg() enables UMAC_RX since MAC
>>    is in SW_RESET
>> 4. Enter resume, UMAC_RX is left enabled. Since we only enable UMAC_TX
>>    and UMAC_RX in SW_RESET. The UMAC_TX is never enabled again on link 
>> up.
>>
>> Fixes: 254f3239dd07 ("net: bcmgenet: revise suspend/resume")
>> Fixes: 88f6c8bf1aae ("net: bcmgenet: keep MAC in reset until PHY is up")
> 
> AFAIU before 254f3239dd07 resume always went through init_umac(), so older
> kernels shouldn't be affected. If we drop the tag for, it would save some
> backports to the older LTS kernels.
> 

That's a good point. I will drop the 88f6c8bf1aae Fixes tag in v2.

Thanks,
Justin

>> Signed-off-by: Justin Chen <justin.chen@broadcom.com>
>> ---
>>  drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c b/ 
>> drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
>> index 96d5d4f7f51f..984432952963 100644
>> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
>> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet_wol.c
>> @@ -253,6 +253,17 @@ int bcmgenet_wol_power_up_cfg(struct 
>> bcmgenet_priv *priv,
>>      reg = bcmgenet_umac_readl(priv, UMAC_CMD);
>>      reg &= ~CMD_CRC_FWD;
>>      bcmgenet_umac_writel(priv, reg, UMAC_CMD);
>> +
>> +    /*
>> +     * Mirror wol_power_down_cfg(). If only UMAC_RX
>> +     * is enabled, then we must place the UMAC back
>> +     * into SW_RESET.
>> +     */
>> +    reg = bcmgenet_umac_readl(priv, UMAC_CMD);
>> +    if ((reg & CMD_RX_EN) && !(reg & CMD_TX_EN)) {
>> +        reg |= CMD_SW_RESET;
>> +        bcmgenet_umac_writel(priv, reg, UMAC_CMD);
>> +    }
>>      spin_unlock_bh(&priv->reg_lock);
>>
>>      /* Resume link status tracking */
> 
> Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
> 
> Thanks,
> Nicolai