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

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

On 9/1/26 15:59, Paolo Abeni wrote:
> 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

hmm sashiko may be right, worth adding right now as it seems there are
some discussions already on motorcomm suspend/resume issues, let me spin
a V2

Thanks !

Maxime