linux-kernel - Re: [PATCH net-next] net: phy: micrel: Add support for lan9645x internal phy

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Message-ID: <aXNFrDOdPanZ_cjk@pengutronix.de>
Date: Fri, 23 Jan 2026 10:55:56 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@...rochip.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Steen Hegelund <Steen.Hegelund@...rochip.com>,
	Daniel Machon <daniel.machon@...rochip.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel@...gutronix.de,
	rsc@...gutronix.de
Subject: Re: [PATCH net-next] net: phy: micrel: Add support for lan9645x
 internal phy

Hi Jens,

On Fri, Jan 23, 2026 at 08:50:55AM +0100, Jens Emil Schulz Østergaard wrote:
> LAN9645X is a family of switch chips with 5 internal copper phys. The
> internal PHY is based on parts of LAN8832. This is a low-power, single
> port triple-speed (10BASE-T/100BASE-TX/1000BASE-T) ethernet physical
> layer transceiver (PHY) that supports transmission and reception of data
> on standard CAT-5, as well as CAT-5e and CAT-6 Unshielded Twisted
> Pair (UTP) cables.
> 
> Add support for the internal PHY of the lan9645x chip family.

Looks like interesting switch for our use cases :)

> Reviewed-by: Steen Hegelund <Steen.Hegelund@...rochip.com>
> Reviewed-by: Daniel Machon <daniel.machon@...rochip.com>
> Signed-off-by: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@...rochip.com>
> ---
>  drivers/net/phy/micrel.c   | 142 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/micrel_phy.h |   1 +
>  2 files changed, 143 insertions(+)
> 
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index 225d4adf28be..7f47f7987067 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -6502,6 +6502,132 @@ static void lan8842_get_phy_stats(struct phy_device *phydev,
>  	stats->tx_errors = priv->phy_stats.tx_errors;
>  }
>  
> +#define LAN9645X_DAC_ICAS_AMP_POWER_DOWN	0x47
> +#define LAN9645X_BTRX_QBIAS_POWER_DOWN		0x46
> +#define LAN9645X_TX_LOW_I_CH_CD_POWER_MGMT	0x45
> +#define LAN9645X_TX_LOW_I_CH_B_POWER_MGMT	0x44
> +#define LAN9645X_TX_LOW_I_CH_A_POWER_MGMT	0x43

> +static const struct lanphy_reg_data force_dac_tx_errata[] = {
> +	/* Force channel A/B/C/D TX on */
> +	{ LAN8814_PAGE_POWER_REGS,
> +	  LAN9645X_DAC_ICAS_AMP_POWER_DOWN,
> +	  0 },
> +	/* Force channel A/B/C/D QBias on */
> +	{ LAN8814_PAGE_POWER_REGS,
> +	  LAN9645X_BTRX_QBIAS_POWER_DOWN,
> +	  0xaa },
> +	/* tx low I on channel C/D overwrite */
> +	{ LAN8814_PAGE_POWER_REGS,
> +	  LAN9645X_TX_LOW_I_CH_CD_POWER_MGMT,
> +	  0xbfff },
> +	/* channel B low I overwrite */
> +	{ LAN8814_PAGE_POWER_REGS,
> +	  LAN9645X_TX_LOW_I_CH_B_POWER_MGMT,
> +	  0xabbf },
> +	/* channel A low I overwrite */
> +	{ LAN8814_PAGE_POWER_REGS,
> +	  LAN9645X_TX_LOW_I_CH_A_POWER_MGMT,
> +	  0xbd3f },
> +};

It looks like this erratum not publicly documented. At least not here:
https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/LAN9645xS-LAN9645xF-Errata-DS80001187.pdf

re there more information about it? Can it be described in the comment?

> +
> +static int lan9645x_config_init(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	/* Apply erratas. */
> +	ret = lan8842_erratas(phydev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return lanphy_write_reg_data(phydev, force_dac_tx_errata,
> +				     ARRAY_SIZE(force_dac_tx_errata));
> +}
> +
> +static int lan9645x_suspend(struct phy_device *phydev)
> +{
> +	int aneg_en_state, ret;
> +
> +	/* Software workaround from design to handle SPD. SPD will stop AFE
> +	 * clock from AFE port, which makes the system MAC fifo unable to flush.
> +	 * The workaround is to restart ANEG and wait for flush, before issuing
> +	 * software power down.
> +	 */
> +	aneg_en_state = phy_read(phydev, MII_BMCR) & BMCR_ANENABLE;
> +
> +	ret = phy_restart_aneg(phydev);
> +	if (ret)
> +		return ret;
> +
> +	/* Allow time for system FIFO flush data */
> +	usleep_range(8 * USEC_PER_MSEC, 12 * USEC_PER_MSEC);

MAC and PHY power management are not always fully coupled (implementation
specific), are there other ways to sync them with each other, except of
unconditional sleep in the PHY driver. I expect that someone making
changes on the MAC driver may miss this nuance.

Best Regards,
Oleksij
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