Re: [PATCH net-next 2/2] net: dsa: mv88e6xxx: Add devlink param for ATU hash algorithm.

[Vivien Didelot <vivien.didelot@gmail.com>]

Hi Andrew,

On Fri,  4 Oct 2019 03:35:23 +0200, Andrew Lunn <andrew@lunn.ch> wrote:
> Some of the marvell switches have bits controlling the hash algorithm
> the ATU uses for MAC addresses. In some industrial settings, where all
> the devices are from the same manufacture, and hence use the same OUI,
> the default hashing algorithm is not optimal. Allow the other
> algorithms to be selected via devlink.
> 
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
> ---
>  drivers/net/dsa/mv88e6xxx/chip.c        | 136 +++++++++++++++++++++++-
>  drivers/net/dsa/mv88e6xxx/chip.h        |   4 +
>  drivers/net/dsa/mv88e6xxx/global1.h     |   3 +
>  drivers/net/dsa/mv88e6xxx/global1_atu.c |  30 ++++++
>  4 files changed, 172 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
> index 6787d560e9e3..ebadcdba03df 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -1370,6 +1370,22 @@ static int mv88e6xxx_atu_new(struct mv88e6xxx_chip *chip, u16 *fid)
>  	return mv88e6xxx_g1_atu_flush(chip, *fid, true);
>  }
>  
> +static int mv88e6xxx_atu_get_hash(struct mv88e6xxx_chip *chip)
> +{
> +	if (chip->info->ops->atu_get_hash)
> +		return chip->info->ops->atu_get_hash(chip);
> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static int mv88e6xxx_atu_set_hash(struct mv88e6xxx_chip *chip, u8 hash)
> +{
> +	if (chip->info->ops->atu_set_hash)
> +		return chip->info->ops->atu_set_hash(chip, hash);
> +
> +	return -EOPNOTSUPP;
> +}
> +
>  static int mv88e6xxx_port_check_hw_vlan(struct dsa_switch *ds, int port,
>  					u16 vid_begin, u16 vid_end)
>  {
> @@ -2641,6 +2657,83 @@ static int mv88e6390_setup_errata(struct mv88e6xxx_chip *chip)
>  	return mv88e6xxx_software_reset(chip);
>  }
>  
> +enum mv88e6xxx_devlink_param_id {
> +	MV88E6XXX_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
> +	MV88E6XXX_DEVLINK_PARAM_ID_ATU_HASH,
> +};
> +
> +static int mv88e6xxx_devlink_param_get(struct dsa_switch *ds, u32 id,
> +				       struct devlink_param_gset_ctx *ctx)
> +{
> +	struct mv88e6xxx_chip *chip = ds->priv;
> +	int err = 0;
> +	int hash;
> +
> +	mv88e6xxx_reg_lock(chip);
> +
> +	switch (id) {
> +	case MV88E6XXX_DEVLINK_PARAM_ID_ATU_HASH:
> +		hash = mv88e6xxx_atu_get_hash(chip);
> +		if (hash < 0) {
> +			err = hash;
> +			break;
> +		}

Could you please keep the common construct used in the driver for
functions which may fail, that is to say using a pointer to the correct
type and only returning error codes, so that we end up with something
like this:

    u8 hash;
    int err;

    err = mv88e6xxx_atu_get_hash(chip, &hash);
    if (err)
        ...


Thanks,

	Vivien