Re: [PATCH net-next 3/3] net: phy: motorcomm: Enable analog frontend on YT8531S

[Paolo Abeni <pabeni@redhat.com>]

On 8/31/26 9:37 AM, Maxime Chevallier wrote:
> The YT6801 PCIe NIC includes the dwmac-motorcomm IP for the MAC part, as
> well as a YT8531S PHY, configured in GMII mode.
> 
> It seems this PHY requires the Analog Front-end (AFE) DAC clock to be
> enabled for link to reliably establish, otherwise the link just doesn't
> come up.
> 
> Let's enable it at config_init().
> 
> This logic has been extracted from the vendor driver provided by
> Motorcomm.
> 
> It's really unclear if this is specific to the integrated version of
> that PHY, and how this potentially interacts with the fiber mode this
> PHY supports, so this configuration is only enabled when the interface
> is GMII, i.e. the PHY is integrated.
> 
> With this, the PHY reliably establishes link and the YT6801 PCIe card
> becomes fully functional.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  drivers/net/phy/motorcomm.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> index 36c229460a77..90a4f86f2758 100644
> --- a/drivers/net/phy/motorcomm.c
> +++ b/drivers/net/phy/motorcomm.c
> @@ -144,6 +144,11 @@
>  #define YT8521_CLOCK_GATING_REG			0xC
>  #define YT8521_CGR_RX_CLK_EN			BIT(12)
>  
> +/* Analog front-end control register 3 */
> +#define YT8531S_EXT_AFE_CTRL3			0x12
> +/* Analog front-end DAC clock enable */
> +#define YT8531S_AFE_CTRL3_CLKDAC_AON		BIT(13)
> +
>  #define YT8521_EXTREG_SLEEP_CONTROL1_REG	0x27
>  #define YT8521_ESC1R_SLEEP_SW			BIT(15)
>  #define YT8521_ESC1R_PLLON_SLP			BIT(14)
> @@ -1740,8 +1745,15 @@ static int yt8531s_config_init(struct phy_device *phydev)
>  	if (ret)
>  		goto err_restore_page;
>  
> -	if (phy_interface_is_rgmii(phydev))
> +	if (phy_interface_is_rgmii(phydev)) {
>  		ret = yt8531_set_ds(phydev);
> +		if (ret)
> +			goto err_restore_page;
> +	}
> +
> +	if (phydev->interface == PHY_INTERFACE_MODE_GMII)
> +		ret = ytphy_modify_ext(phydev, YT8531S_EXT_AFE_CTRL3,
> +				       0, YT8531S_AFE_CTRL3_CLKDAC_AON);

Sashiko suspects this will not survive a suspend/resume:

https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260831073747.361482-1-maxime.chevallier%40bootlin.com

/P