Re: [PATCH net-next v3 3/4] net: phy: Add helper to derive the number of ports from a phy mode

[Florian Fainelli <f.fainelli@gmail.com>]

On 7/29/22 08:33, Maxime Chevallier wrote:
> Some phy modes such as QSGMII multiplex several MAC<->PHY links on one
> single physical interface. QSGMII used to be the only one supported, but
> other modes such as QUSGMII also carry multiple links.
> 
> This helper allows getting the number of links that are multiplexed
> on a given interface.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
> V1->V2 : New patch
> V2->V3 : Made PHY_INTERFACE_MODE_INTERNAL 1 port, and added the MAX
> case.
> 
>  drivers/net/phy/phy-core.c | 52 ++++++++++++++++++++++++++++++++++++++
>  include/linux/phy.h        |  2 ++
>  2 files changed, 54 insertions(+)
> 
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index 1f2531a1a876..f8ec12d3d6ae 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -74,6 +74,58 @@ const char *phy_duplex_to_str(unsigned int duplex)
>  }
>  EXPORT_SYMBOL_GPL(phy_duplex_to_str);
>  
> +/**
> + * phy_interface_num_ports - Return the number of links that can be carried by
> + *			     a given MAC-PHY physical link. Returns 0 if this is
> + *			     unknown, the number of links else.
> + *
> + * @interface: The interface mode we want to get the number of ports
> + */
> +int phy_interface_num_ports(phy_interface_t interface)
> +{
> +	switch (interface) {
> +	case PHY_INTERFACE_MODE_NA:
> +		return 0;
> +	case PHY_INTERFACE_MODE_INTERNAL:

Maybe this was covered in the previous iteration, but cannot the default case return 1, and all of the cases that need an explicit non-1 return value are handled? Enumeration all of those that do need to return 1 does not really scale.
-- 
Florian