Re: [PATCH 6/7] net: phy: at803x: add disable hibernation mode support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 10.07.23 08:36, Marco Felsch wrote:
> This commit ports Linux commit:
> 
> | commit 9ecf04016c87bcb33b44e24489d33618e2592f41
> | Author: Wei Fang <wei.fang@nxp.com>
> | Date:   Thu Aug 18 11:00:54 2022 +0800
> |
> |     net: phy: at803x: add disable hibernation mode support
> |
> |     When the cable is unplugged, the Atheros AR803x PHYs will enter
> |     hibernation mode after about 10 seconds if the hibernation mode
> |     is enabled and will not provide any clock to the MAC. But for
> |     some MACs, this feature might cause unexpected issues due to the
> |     logic of MACs.
> |     Taking SYNP MAC (stmmac) as an example, if the cable is unplugged
> |     and the "eth0" interface is down, the AR803x PHY will enter
> |     hibernation mode. Then perform the "ifconfig eth0 up" operation,
> |     the stmmac can't be able to complete the software reset operation
> |     and fail to init it's own DMA. Therefore, the "eth0" interface is
> |     failed to ifconfig up. Why does it cause this issue? The truth is
> |     that the software reset operation of the stmmac is designed to
> |     depend on the RX_CLK of PHY.
> |     So, this patch offers an option for the user to determine whether
> |     to disable the hibernation mode of AR803x PHYs.
> |
> |     Signed-off-by: Wei Fang <wei.fang@nxp.com>
> |     Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> |     Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>

IMO we should just makes AT803X_DISABLE_HIBERNATION_MODE the default and
never hibernate the PHY. Let Linux worry about that.

> ---
>  drivers/net/phy/at803x.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index cc425c318f..d8a9c3588f 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -32,6 +32,9 @@
>  #define AT803X_DEBUG_REG_5			0x05
>  #define AT803X_DEBUG_TX_CLK_DLY_EN		BIT(8)
>  
> +#define AT803X_DEBUG_REG_HIB_CTRL		0x0b
> +#define   AT803X_DEBUG_HIB_CTRL_PS_HIB_EN	BIT(15)
> +
>  /* AT803x supports either the XTAL input pad, an internal PLL or the
>   * DSP as clock reference for the clock output pad. The XTAL reference
>   * is only used for 25 MHz output, all other frequencies need the PLL.
> @@ -140,6 +143,20 @@ static int at803x_disable_tx_delay(struct phy_device *phydev)
>  				     AT803X_DEBUG_TX_CLK_DLY_EN, 0);
>  }
>  
> +static int at803x_hibernation_mode_config(struct phy_device *phydev)
> +{
> +	struct at803x_priv *priv = phydev->priv;
> +
> +	/* The default after hardware reset is hibernation mode enabled. After
> +	 * software reset, the value is retained.
> +	 */
> +	if (!(priv->flags & AT803X_DISABLE_HIBERNATION_MODE))
> +		return 0;
> +
> +	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_HIB_CTRL,
> +				     AT803X_DEBUG_HIB_CTRL_PS_HIB_EN, 0);
> +}
> +
>  static bool at803x_match_phy_id(struct phy_device *phydev, u32 phy_id)
>  {
>  	struct phy_driver *drv = to_phy_driver(phydev->dev.driver);
> @@ -160,6 +177,9 @@ static int at803x_parse_dt(struct phy_device *phydev)
>  	if (of_property_read_bool(node, "qca,disable-smarteee"))
>  		priv->flags |= AT803X_DISABLE_SMARTEEE;
>  
> +	if (of_property_read_bool(node, "qca,disable-hibernation-mode"))
> +		priv->flags |= AT803X_DISABLE_HIBERNATION_MODE;
> +
>  	if (!of_property_read_u32(node, "qca,smarteee-tw-us-1g", &tw)) {
>  		if (!tw || tw > 255) {
>  			phydev_err(phydev, "invalid qca,smarteee-tw-us-1g\n");
> @@ -341,6 +361,10 @@ static int at803x_config_init(struct phy_device *phydev)
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = at803x_hibernation_mode_config(phydev);
> +	if (ret < 0)
> +		return ret;
> +
>  	return 0;
>  }
>  

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