> -----Original Message-----
> From: Long Li <[email protected]>
> Sent: Thursday, February 26, 2026 2:29 PM
> To: KY Srinivasan <[email protected]>; Haiyang Zhang
> <[email protected]>; Wei Liu <[email protected]>; Dexuan Cui
> <[email protected]>; Long Li <[email protected]>; Andrew Lunn
> <[email protected]>; David S . Miller <[email protected]>; Eric
> Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> Abeni <[email protected]>
> Cc: Shradha Gupta <[email protected]>; Erni Sri Satya
> Vennela <[email protected]>; [email protected];
> [email protected]; [email protected];
> [email protected]
> Subject: [PATCH net v2] net: mana: Ring doorbell at 4 CQ wraparounds
>
> MANA hardware requires at least one doorbell ring every 8 wraparounds
> of the CQ. The driver rings the doorbell as a form of flow control to
> inform hardware that CQEs have been consumed.
>
> The NAPI poll functions mana_poll_tx_cq() and mana_poll_rx_cq() can
> poll up to CQE_POLLING_BUFFER (512) completions per call. If the CQ
> has fewer than 512 entries, a single poll call can process more than
> 4 wraparounds without ringing the doorbell. The doorbell threshold
> check also uses ">" instead of ">=", delaying the ring by one extra
> CQE beyond 4 wraparounds. Combined, these issues can cause the driver
> to exceed the 8-wraparound hardware limit, leading to missed
> completions and stalled queues.
>
> Fix this by capping the number of CQEs polled per call to 4 wraparounds
> of the CQ in both TX and RX paths. Also change the doorbell threshold
> from ">" to ">=" so the doorbell is rung as soon as 4 wraparounds are
> reached.
>
> Cc: [email protected]
> Fixes: 58a63729c957 ("net: mana: Fix doorbell out of order violation and
> avoid unnecessary doorbell rings")
> Signed-off-by: Long Li <[email protected]>
> ---
Reviewed-by: Haiyang Zhang <[email protected]>
