[PATCH net v2] net: ti: icssg-prueth: Fix emac link speed handling

[Andrew Lunn]

On Fri, Aug 01, 2025 at 05:49:48PM +0530, MD Danish Anwar wrote:
> When link settings are changed emac->speed is populated by
> emac_adjust_link(). The link speed and other settings are then written into
> the DRAM. However if both ports are brought down after this and brought up
> again or if the operating mode is changed and a firmware reload is needed,
> the DRAM is cleared by icssg_config(). As a result the link settings are
> lost.
> 
> Fix this by calling emac_adjust_link() after icssg_config(). This re
> populates the settings in the DRAM after a new firmware load.
> 
> Fixes: 9facce84f406 ("net: ti: icssg-prueth: Fix firmware load sequence.")
> Signed-off-by: MD Danish Anwar <danishanwar at ti.com>
> ---
> v1 - v2: Added phydev lock before calling emac_adjust_link() as suggested
> by Andrew Lunn <andrew at lunn.ch>
> v1 https://lore.kernel.org/all/20250731120812.1606839-1-danishanwar@ti.com/
> 
>  drivers/net/ethernet/ti/icssg/icssg_prueth.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> index 2b973d6e2341..58aec94b7771 100644
> --- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> +++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
> @@ -50,6 +50,8 @@
>  /* CTRLMMR_ICSSG_RGMII_CTRL register bits */
>  #define ICSSG_CTRL_RGMII_ID_MODE                BIT(24)
>  
> +static void emac_adjust_link(struct net_device *ndev);
> +
>  static int emac_get_tx_ts(struct prueth_emac *emac,
>  			  struct emac_tx_ts_response *rsp)
>  {
> @@ -229,6 +231,12 @@ static int prueth_emac_common_start(struct prueth *prueth)
>  		ret = icssg_config(prueth, emac, slice);
>  		if (ret)
>  			goto disable_class;
> +
> +		if (emac->ndev->phydev) {
> +			mutex_lock(&emac->ndev->phydev->lock);
> +			emac_adjust_link(emac->ndev);
> +			mutex_unlock(&emac->ndev->phydev->lock);
> +		}

What about the else case? The link settings are lost, and the MAC does
not work?

	Andrew