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

[Vitaliy Sochnev <sochnev.v.74@gmail.com>]

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@gmail.com>
---
 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