netdev - Re: [PATCH net-next v4 3/4] net: sfp: create/destroy I2C mdiobus before PHY probe/after PHY release

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Message-ID: <20210113104142.pr3dnrcwmyxb54yj@pali>
Date:   Wed, 13 Jan 2021 11:41:42 +0100
From:   Pali Rohár <pali@...nel.org>
To:     Marek Behún <kabel@...nel.org>
Cc:     netdev@...r.kernel.org, Russell King <rmk+kernel@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>,
        davem@...emloft.net
Subject: Re: [PATCH net-next v4 3/4] net: sfp: create/destroy I2C mdiobus
 before PHY probe/after PHY release

On Monday 11 January 2021 06:00:43 Marek Behún wrote:
> Instead of configuring the I2C mdiobus when SFP driver is probed,
> create/destroy the mdiobus before the PHY is probed for/after it is
> released.
> 
> This way we can tell the mdio-i2c code which protocol to use for each
> SFP transceiver.
> 
> Signed-off-by: Marek Behún <kabel@...nel.org>
> Cc: Andrew Lunn <andrew@...n.ch>
> Cc: Russell King <rmk+kernel@...linux.org.uk>

Reviewed-by: Pali Rohár <pali@...nel.org>

> ---
>  drivers/net/phy/sfp.c | 30 ++++++++++++++++++++++++++----
>  1 file changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index 958fd514a3b4..0621d12cf878 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -217,6 +217,7 @@ struct sfp {
>  	struct i2c_adapter *i2c;
>  	struct mii_bus *i2c_mii;
>  	struct sfp_bus *sfp_bus;
> +	enum mdio_i2c_proto mdio_protocol;
>  	struct phy_device *mod_phy;
>  	const struct sff_data *type;
>  	size_t i2c_block_size;
> @@ -409,9 +410,6 @@ static int sfp_i2c_write(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
>  
>  static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
>  {
> -	struct mii_bus *i2c_mii;
> -	int ret;
> -
>  	if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
>  		return -EINVAL;
>  
> @@ -419,7 +417,15 @@ static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
>  	sfp->read = sfp_i2c_read;
>  	sfp->write = sfp_i2c_write;
>  
> -	i2c_mii = mdio_i2c_alloc(sfp->dev, i2c, MDIO_I2C_DEFAULT);
> +	return 0;
> +}
> +
> +static int sfp_i2c_mdiobus_create(struct sfp *sfp)
> +{
> +	struct mii_bus *i2c_mii;
> +	int ret;
> +
> +	i2c_mii = mdio_i2c_alloc(sfp->dev, sfp->i2c, sfp->mdio_protocol);
>  	if (IS_ERR(i2c_mii))
>  		return PTR_ERR(i2c_mii);
>  
> @@ -437,6 +443,12 @@ static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
>  	return 0;
>  }
>  
> +static void sfp_i2c_mdiobus_destroy(struct sfp *sfp)
> +{
> +	mdiobus_unregister(sfp->i2c_mii);
> +	sfp->i2c_mii = NULL;
> +}
> +
>  /* Interface */
>  static int sfp_read(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len)
>  {
> @@ -1821,6 +1833,8 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
>  	else
>  		sfp->module_t_start_up = T_START_UP;
>  
> +	sfp->mdio_protocol = MDIO_I2C_DEFAULT;
> +
>  	return 0;
>  }
>  
> @@ -1991,6 +2005,8 @@ static void sfp_sm_main(struct sfp *sfp, unsigned int event)
>  			sfp_module_stop(sfp->sfp_bus);
>  		if (sfp->mod_phy)
>  			sfp_sm_phy_detach(sfp);
> +		if (sfp->i2c_mii)
> +			sfp_i2c_mdiobus_destroy(sfp);
>  		sfp_module_tx_disable(sfp);
>  		sfp_soft_stop_poll(sfp);
>  		sfp_sm_next(sfp, SFP_S_DOWN, 0);
> @@ -2053,6 +2069,12 @@ static void sfp_sm_main(struct sfp *sfp, unsigned int event)
>  				     sfp->sm_fault_retries == N_FAULT_INIT);
>  		} else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR) {
>  	init_done:
> +			/* Create mdiobus and start trying for PHY */
> +			ret = sfp_i2c_mdiobus_create(sfp);
> +			if (ret < 0) {
> +				sfp_sm_next(sfp, SFP_S_FAIL, 0);
> +				break;
> +			}
>  			sfp->sm_phy_retries = R_PHY_RETRY;
>  			goto phy_probe;
>  		}
> -- 
> 2.26.2
>