linux-kernel - Re: [PATCH net-next v3 3/8] net: dsa: mv88e6xxx: read switch ID in probe

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Date:	Sun, 17 Apr 2016 17:26:28 +0200
From:	Andrew Lunn <andrew@...n.ch>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel@...oirfairelinux.com,
	"David S. Miller" <davem@...emloft.net>,
	Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH net-next v3 3/8] net: dsa: mv88e6xxx: read switch ID in
 probe

On Sat, Apr 16, 2016 at 06:41:40PM -0400, Vivien Didelot wrote:
> Read the switch ID only once, at probe time, to avoid multiple read
> accesses and MII bus checking.
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

Thanks
	Andrew

> ---
>  drivers/net/dsa/mv88e6xxx.c | 54 +++++++++++++++++++++++++--------------------
>  1 file changed, 30 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
> index b63e985..af5ae70 100644
> --- a/drivers/net/dsa/mv88e6xxx.c
> +++ b/drivers/net/dsa/mv88e6xxx.c
> @@ -2667,8 +2667,6 @@ int mv88e6xxx_setup_common(struct dsa_switch *ds)
>  	ps->ds = ds;
>  	mutex_init(&ps->smi_mutex);
>  
> -	ps->id = REG_READ(REG_PORT(0), PORT_SWITCH_ID) & 0xfff0;
> -
>  	INIT_WORK(&ps->bridge_work, mv88e6xxx_bridge_work);
>  
>  	return 0;
> @@ -3068,21 +3066,14 @@ int mv88e6xxx_get_temp_alarm(struct dsa_switch *ds, bool *alarm)
>  }
>  #endif /* CONFIG_NET_DSA_HWMON */
>  
> -static char *mv88e6xxx_lookup_name(struct mii_bus *bus, int sw_addr,
> +static char *mv88e6xxx_lookup_name(unsigned int id,
>  				   const struct mv88e6xxx_switch_id *table,
>  				   unsigned int num)
>  {
> -	int i, ret;
> -
> -	if (!bus)
> -		return NULL;
> -
> -	ret = __mv88e6xxx_reg_read(bus, sw_addr, REG_PORT(0), PORT_SWITCH_ID);
> -	if (ret < 0)
> -		return NULL;
> +	int i;
>  
>  	for (i = 0; i < num; ++i)
> -		if (table[i].id == (ret & 0xfff0))
> +		if (table[i].id == (id & 0xfff0))
>  			return table[i].name;
>  
>  	return NULL;
> @@ -3094,23 +3085,38 @@ char *mv88e6xxx_drv_probe(struct device *dsa_dev, struct device *host_dev,
>  			  unsigned int num)
>  {
>  	struct mv88e6xxx_priv_state *ps;
> -	struct mii_bus *bus = dsa_host_dev_to_mii_bus(host_dev);
> +	struct mii_bus *bus;
> +	int id, prod_num, rev;
>  	char *name;
>  
> +	bus = dsa_host_dev_to_mii_bus(host_dev);
>  	if (!bus)
>  		return NULL;
>  
> -	name = mv88e6xxx_lookup_name(bus, sw_addr, table, num);
> -	if (name) {
> -		ps = devm_kzalloc(dsa_dev, sizeof(*ps), GFP_KERNEL);
> -		if (!ps)
> -			return NULL;
> -		*priv = ps;
> -		ps->bus = dsa_host_dev_to_mii_bus(host_dev);
> -		if (!ps->bus)
> -			return NULL;
> -		ps->sw_addr = sw_addr;
> -	}
> +	id = __mv88e6xxx_reg_read(bus, sw_addr, REG_PORT(0), PORT_SWITCH_ID);
> +	if (id < 0)
> +		return NULL;
> +
> +	prod_num = (id & 0xfff0) >> 4;
> +	rev = id & 0x000f;
> +
> +	name = mv88e6xxx_lookup_name(id, table, num);
> +	if (!name)
> +		return NULL;
> +
> +	ps = devm_kzalloc(dsa_dev, sizeof(*ps), GFP_KERNEL);
> +	if (!ps)
> +		return NULL;
> +
> +	ps->bus = bus;
> +	ps->sw_addr = sw_addr;
> +	ps->id = id & 0xfff0;
> +
> +	*priv = ps;
> +
> +	dev_info(&ps->bus->dev, "switch 0x%x probed: %s, revision %u\n",
> +		 prod_num, name, rev);
> +
>  	return name;
>  }
>  
> -- 
> 2.8.0
>