Re: [PATCH RFC net-next v2 3/7] net: stmmac: use integrated PCS for BASE-X modes

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi Russell,

On 04/03/2026 09:49, Russell King (Oracle) wrote:
> dwmac-qcom-ethqos supports SGMII and 2500BASE-X using the integrated
> PCS, so we need to expand the PCS support to include support for
> BASE-X modes.
> 
> Add support to the prereset configuration to detect 2500BASE-X, and
> arrange for stmmac_mac_select_pcs() to return the integrated PCS if
> its supported_interfaces bitmap reports support for the interface mode.
> 
> This results in priv->hw->pcs now being write-only, so remove it.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

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

Maxime

> ---
>  drivers/net/ethernet/stmicro/stmmac/common.h      | 4 ----
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 ++------
>  2 files changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
> index 42a48f655849..91116acf3273 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/common.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/common.h
> @@ -277,9 +277,6 @@ struct stmmac_safety_stats {
>  #define FLOW_TX		2
>  #define FLOW_AUTO	(FLOW_TX | FLOW_RX)
>  
> -/* PCS defines */
> -#define STMMAC_PCS_SGMII	(1 << 1)
> -
>  #define SF_DMA_MODE 1		/* DMA STORE-AND-FORWARD Operation Mode */
>  
>  /* DMA HW feature register fields */
> @@ -634,7 +631,6 @@ struct mac_device_info {
>  	unsigned int unicast_filter_entries;
>  	unsigned int mcast_bits_log2;
>  	unsigned int rx_csum;
> -	unsigned int pcs;
>  	unsigned int num_vlan;
>  	u32 vlan_filter[32];
>  	bool vlan_fail_q_en;
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 029e9b518160..2e7edc3e82f2 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -945,11 +945,8 @@ static struct phylink_pcs *stmmac_mac_select_pcs(struct phylink_config *config,
>  			return pcs;
>  	}
>  
> -	/* The PCS control register is only relevant for SGMII, TBI and RTBI
> -	 * modes. We no longer support TBI or RTBI, so only configure this
> -	 * register when operating in SGMII mode with the integrated PCS.
> -	 */
> -	if (priv->hw->pcs & STMMAC_PCS_SGMII && priv->integrated_pcs)
> +	if (priv->integrated_pcs &&
> +	    test_bit(interface, priv->integrated_pcs->pcs.supported_interfaces))
>  		return &priv->integrated_pcs->pcs;
>  
>  	return NULL;
> @@ -1208,7 +1205,6 @@ static void stmmac_check_pcs_mode(struct stmmac_priv *priv)
>  
>  	if (priv->dma_cap.pcs && interface == PHY_INTERFACE_MODE_SGMII) {
>  		netdev_dbg(priv->dev, "PCS SGMII support enabled\n");
> -		priv->hw->pcs = STMMAC_PCS_SGMII;
>  
>  		switch (speed) {
>  		case SPEED_10: