Re: [PATCH net-next 12/13] net: dsa: lantiq_gswip: Add and use a GSWIP_TABLE_MAC_BRIDGE_FID macro

[Vladimir Oltean]

On Thu, Jun 06, 2024 at 10:52:33AM +0200, Martin Schiller wrote:
> From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
> 
> Only bits [5:0] in mac_bridge.key[3] are reserved for the FID. Add a
> macro so this becomes obvious when reading the driver code.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
> ---
>  drivers/net/dsa/lantiq_gswip.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
> index f2faee112e33..4bb894e75b81 100644
> --- a/drivers/net/dsa/lantiq_gswip.c
> +++ b/drivers/net/dsa/lantiq_gswip.c
> @@ -238,6 +238,7 @@
>  #define GSWIP_TABLE_MAC_BRIDGE		0x0b
>  #define  GSWIP_TABLE_MAC_BRIDGE_STATIC	BIT(0)		/* Static not, aging entry */
>  #define  GSWIP_TABLE_MAC_BRIDGE_PORT	GENMASK(7, 4)	/* Port on learned entries */
> +#define  GSWIP_TABLE_MAC_BRIDGE_FID	GENMASK(5, 0)	/* Filtering identifier */
>  
>  #define XRX200_GPHY_FW_ALIGN	(16 * 1024)
>  
> @@ -1385,7 +1386,7 @@ static int gswip_port_fdb(struct dsa_switch *ds, int port,
>  	mac_bridge.key[0] = addr[5] | (addr[4] << 8);
>  	mac_bridge.key[1] = addr[3] | (addr[2] << 8);
>  	mac_bridge.key[2] = addr[1] | (addr[0] << 8);
> -	mac_bridge.key[3] = fid;
> +	mac_bridge.key[3] = FIELD_PREP(GSWIP_TABLE_MAC_BRIDGE_FID, fid);
>  	mac_bridge.val[0] = add ? BIT(port) : 0; /* port map */
>  	mac_bridge.val[1] = GSWIP_TABLE_MAC_BRIDGE_STATIC;
>  	mac_bridge.valid = add;
> -- 
> 2.39.2

On second thought, I disagree with the naming scheme of the
GSWIP_TABLE_MAC_BRIDGE_* macros. It is completely non obvious that they
are non-overlapping, because they have the same name prefix, but:
_STATIC applies to gswip_pce_table_entry :: val[1]
_PORT applies to gswip_pce_table_entry :: val[0]
_FID applies to gswip_pce_table_entry :: key[3]

I think it's all too easy to use the wrong macro on the wrong register field.
If the macros incorporated names like VAL1, KEY3 etc, it would be much
more obvious. Could you please do that?