[PATCH net-next 3/5] net: stmmac: avoid PHY speed change when configuring MTU

[Maxime Chevallier]

On 15/10/2025 18:10, Russell King (Oracle) wrote:
> There is no need to do the speed-down, speed-up dance when changing
> the MTU as there is little power saving that can be gained from such
> a brief interval between these, and the autonegotiation they cause
> takes much longer.
> 
> Move the calls to phylink_speed_up() and phylink_speed_down() into
> stmmac_open() and stmmac_release() respectively, reducing the work
> done in the __-variants of these functions.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

Reviewed-by: Maxime Chevallier <maxime.chevallier at bootlin.com>

> ---
>  .../net/ethernet/stmicro/stmmac/stmmac_main.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 3728afa701c6..500cfd19e6b5 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -3963,8 +3963,6 @@ static int __stmmac_open(struct net_device *dev,
>  	stmmac_init_coalesce(priv);
>  
>  	phylink_start(priv->phylink);
> -	/* We may have called phylink_speed_down before */
> -	phylink_speed_up(priv->phylink);
>  
>  	ret = stmmac_request_irq(dev);
>  	if (ret)
> @@ -4015,6 +4013,9 @@ static int stmmac_open(struct net_device *dev)
>  
>  	kfree(dma_conf);
>  
> +	/* We may have called phylink_speed_down before */
> +	phylink_speed_up(priv->phylink);
> +
>  	return ret;
>  
>  err_disconnect_phy:
> @@ -4032,13 +4033,6 @@ static void __stmmac_release(struct net_device *dev)
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  	u32 chan;
>  
> -	/* If the PHY or MAC has WoL enabled, then the PHY will not be
> -	 * suspended when phylink_stop() is called below. Set the PHY
> -	 * to its slowest speed to save power.
> -	 */
> -	if (device_may_wakeup(priv->device))
> -		phylink_speed_down(priv->phylink, false);
> -
>  	/* Stop and disconnect the PHY */
>  	phylink_stop(priv->phylink);
>  
> @@ -4078,6 +4072,13 @@ static int stmmac_release(struct net_device *dev)
>  {
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  
> +	/* If the PHY or MAC has WoL enabled, then the PHY will not be
> +	 * suspended when phylink_stop() is called below. Set the PHY
> +	 * to its slowest speed to save power.
> +	 */
> +	if (device_may_wakeup(priv->device))
> +		phylink_speed_down(priv->phylink, false);
> +
>  	__stmmac_release(dev);
>  
>  	phylink_disconnect_phy(priv->phylink);