netdev - Re: [PATCH net-next] net: ks8851: Connect and start/stop the internal PHY

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Date:   Mon, 11 Jan 2021 14:26:04 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Marek Vasut <marex@...x.de>, netdev@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>, Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH net-next] net: ks8851: Connect and start/stop the internal
 PHY

On 11.01.2021 13:53, Marek Vasut wrote:
> Unless the internal PHY is connected and started, the phylib will not
> poll the PHY for state and produce state updates. Connect the PHY and
> start/stop it.
> 
> Signed-off-by: Marek Vasut <marex@...x.de>
> Cc: Andrew Lunn <andrew@...n.ch>
> Cc: Heiner Kallweit <hkallweit1@...il.com>
> Cc: Lukas Wunner <lukas@...ner.de>
> ---
>  drivers/net/ethernet/micrel/ks8851.h        |  2 ++
>  drivers/net/ethernet/micrel/ks8851_common.c | 28 +++++++++++++++++++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/drivers/net/ethernet/micrel/ks8851.h b/drivers/net/ethernet/micrel/ks8851.h
> index e2eb0caeac82..ef13929036cf 100644
> --- a/drivers/net/ethernet/micrel/ks8851.h
> +++ b/drivers/net/ethernet/micrel/ks8851.h
> @@ -359,6 +359,7 @@ union ks8851_tx_hdr {
>   * @vdd_io: Optional digital power supply for IO
>   * @gpio: Optional reset_n gpio
>   * @mii_bus: Pointer to MII bus structure
> + * @phy_dev: Pointer to PHY device structure
>   * @lock: Bus access lock callback
>   * @unlock: Bus access unlock callback
>   * @rdreg16: 16bit register read callback
> @@ -405,6 +406,7 @@ struct ks8851_net {
>  	struct regulator	*vdd_io;
>  	int			gpio;
>  	struct mii_bus		*mii_bus;
> +	struct phy_device	*phy_dev;
>  
>  	void			(*lock)(struct ks8851_net *ks,
>  					unsigned long *flags);
> diff --git a/drivers/net/ethernet/micrel/ks8851_common.c b/drivers/net/ethernet/micrel/ks8851_common.c
> index 058fd99bd483..a3716fd2d858 100644
> --- a/drivers/net/ethernet/micrel/ks8851_common.c
> +++ b/drivers/net/ethernet/micrel/ks8851_common.c
> @@ -432,6 +432,11 @@ static void ks8851_flush_tx_work(struct ks8851_net *ks)
>  		ks->flush_tx_work(ks);
>  }
>  
> +static void ks8851_handle_link_change(struct net_device *net)
> +{
> +	phy_print_status(net->phydev);
> +}
> +
>  /**
>   * ks8851_net_open - open network device
>   * @dev: The network device being opened.
> @@ -445,11 +450,22 @@ static int ks8851_net_open(struct net_device *dev)
>  	unsigned long flags;
>  	int ret;
>  
> +	ret = phy_connect_direct(ks->netdev, ks->phy_dev,
> +				 &ks8851_handle_link_change,
> +				 PHY_INTERFACE_MODE_INTERNAL);
> +	if (ret) {
> +		netdev_err(dev, "failed to attach PHY\n");
> +		return ret;
> +	}
> +
> +	phy_attached_info(ks->phy_dev);
> +
>  	ret = request_threaded_irq(dev->irq, NULL, ks8851_irq,
>  				   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
>  				   dev->name, ks);
>  	if (ret < 0) {
>  		netdev_err(dev, "failed to get irq\n");
> +		phy_disconnect(ks->phy_dev);
>  		return ret;
>  	}
>  
> @@ -507,6 +523,7 @@ static int ks8851_net_open(struct net_device *dev)
>  	netif_dbg(ks, ifup, ks->netdev, "network device up\n");
>  
>  	ks8851_unlock(ks, &flags);
> +	phy_start(ks->phy_dev);
>  	mii_check_link(&ks->mii);
>  	return 0;
>  }
> @@ -528,6 +545,9 @@ static int ks8851_net_stop(struct net_device *dev)
>  
>  	netif_stop_queue(dev);
>  
> +	phy_stop(ks->phy_dev);
> +	phy_disconnect(ks->phy_dev);
> +
>  	ks8851_lock(ks, &flags);
>  	/* turn off the IRQs and ack any outstanding */
>  	ks8851_wrreg16(ks, KS_IER, 0x0000);
> @@ -1084,6 +1104,7 @@ int ks8851_resume(struct device *dev)
>  
>  static int ks8851_register_mdiobus(struct ks8851_net *ks, struct device *dev)
>  {
> +	struct phy_device *phy_dev;
>  	struct mii_bus *mii_bus;
>  	int ret;
>  
> @@ -1103,10 +1124,17 @@ static int ks8851_register_mdiobus(struct ks8851_net *ks, struct device *dev)
>  	if (ret)
>  		goto err_mdiobus_register;
>  
> +	phy_dev = phy_find_first(mii_bus);
> +	if (!phy_dev)
> +		goto err_find_phy;
> +
>  	ks->mii_bus = mii_bus;
> +	ks->phy_dev = phy_dev;
>  
>  	return 0;
>  
> +err_find_phy:
> +	mdiobus_unregister(mii_bus);
>  err_mdiobus_register:
>  	mdiobus_free(mii_bus);
>  	return ret;
> 

LGTM. When having a brief look at the driver I stumbled across two things:

1. Do MAC/PHY support any pause mode? Then a call to
   phy_support_(a)sym_pause() would be missing.

2. Don't have the datasheet, but IRQ_LCI seems to be the link change
   interrupt. So far it's ignored by the driver. You could configure
   it and use phy_mac_interrupt() to operate the internal PHY in
   interrupt mode.