[PATCH net v2 3/3] net: airoha: grow the small RX rings

[Lorenzo Bianconi]

> Raise the RX_DSCP_NUM() fallback from 16 to 32, the vendor SDK default,
> and give ring 4 the 128 descriptors already used for rings 2/11/15.
> 
> Ring 4 is the shared "force to CPU" ring that airoha_fe_vip_setup()
> routes BOOTP, PPPoE Discovery, PPP LCP/IPCP/CHAP/PAP/IPv6CP, ISAKMP,
> DHCPv6, SIP and LLDP onto, so it sees the same bursty non-hashed traffic
> as the rings already on 128 while sitting on the smallest allowance.
> 
> At 16 descriptors the completion stall handled by the previous patch is
> readily reachable: on a Nokia XG-040G-MF the recovery fires roughly every
> 35 s under repeated PPPoE dial-up, and negotiation never completes. At
> 128 it did not trigger once across 500 forced PPPoE reconnects over 20 h.
> 
> Ring 4 and the VIP classification feeding it are shared driver-wide, with
> no DT or hardware property distinguishing one variant's ring 4 from
> another's, so this is not scoped to a particular SoC.
> 
> Fixes: 23020f049327 ("net: airoha: Introduce ethernet support for EN7581 SoC")
> Signed-off-by: Vitaliy Sochnev <sochnev.v.74 at gmail.com>

Acked-by: Lorenzo Bianconi <lorenzo at kernel.org>

> ---
>  drivers/net/ethernet/airoha/airoha_eth.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
> index c195dad5ed58..0b7c90940272 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.h
> +++ b/drivers/net/ethernet/airoha/airoha_eth.h
> @@ -41,9 +41,10 @@
>  #define TX_DSCP_NUM			1024
>  #define RX_DSCP_NUM(_n)			\
>  	((_n) ==  2 ? 128 :		\
> +	 (_n) ==  4 ? 128 :		\
>  	 (_n) == 11 ? 128 :		\
>  	 (_n) == 15 ? 128 :		\
> -	 (_n) ==  0 ? 1024 : 16)
> +	 (_n) ==  0 ? 1024 : 32)
>  
>  #define PSE_RSV_PAGES			128
>  #define PSE_QUEUE_RSV_PAGES		64
> -- 
> 2.55.0
> 
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