netdev - Re: [PATCH] net: dsa: mv88e6xxx: refine SMI support

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Date:   Fri, 3 May 2019 16:01:38 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vivien Didelot <vivien.didelot@...il.com>, netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH] net: dsa: mv88e6xxx: refine SMI support

On 5/3/19 3:49 PM, Vivien Didelot wrote:
> The Marvell SOHO switches have several ways to access the internal
> registers. One of them being the System Management Interface (SMI),
> using the MDC and MDIO pins, with direct and indirect variants.
> 
> In preparation for adding support for other register accesses, move
> the SMI code into its own files. At the same time, refine the code
> to make it clear that the indirect variant is implemented using the
> direct variant accessing only two registers for command and data.
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@...il.com>
> ---

With some nits below:

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>

[snip]

>  	assert_reg_lock(chip);
>  
> -	err = mv88e6xxx_smi_read(chip, addr, reg, val);
> +	if (chip->smi_ops)
> +		err = chip->smi_ops->read(chip, addr, reg, val);
> +	else

You might want to check for smi_ops && smi_ops->read here to be safe.
You could also keep that code unchanged, and just make
mv88e6xxx_smi_read() an inline helper within smi.h:

static inline int mv88e6xxx_smi_read(struct mv88e6xxx_chip *chip, int
addr, int reg, int *val)
{
	if (chip->smi_ops && chip->smi_ops->read)
		return chip->smi_ops->read(chip, addr, reg, val);

	return -EOPNOTSUPP;
}

> +		err = -EOPNOTSUPP;
> +
>  	if (err)
>  		return err;
>  
> @@ -217,7 +79,11 @@ int mv88e6xxx_write(struct mv88e6xxx_chip *chip, int addr, int reg, u16 val)
>  
>  	assert_reg_lock(chip);
>  
> -	err = mv88e6xxx_smi_write(chip, addr, reg, val);
> +	if (chip->smi_ops)
> +		err = chip->smi_ops->write(chip, addr, reg, val);
> +	else

Same here, you might want to check smi_ops && smi_ops->write to avoid
de-referencing a potentially NULL pointer.
-- 
Florian