Re: [dpdk-dev] [PATCH v5 2/5] ethdev: add new attributes to hairpin config

[Thomas Monjalon <thomas@monjalon.net>]

15/10/2020 07:35, Bing Zhao:
> To support two ports hairpin mode and keep the backward compatibility
> for the application, two new attribute members of the hairpin queue
> configuration structure will be added.
> 
> `tx_explicit` means if the application itself will insert the TX part
> flow rules. If not set, PMD will insert the rules implicitly.
> `manual_bind` means if the hairpin TX queue and peer RX queue will be
> bound automatically during the device start stage.
> 
> Different TX and RX queue pairs could have different values, but it
> is highly recommended that all paired queues between one egress and
> its peer ingress ports have the same values, in order not to bring
> any chaos to the system. The actual support of these attribute
> parameters will be checked and decided by the PMD drivers.
> 
> In the single port hairpin, if both are zero without any setting, the
> behavior will remain the same as before. It means that no bind API
> needs to be called and no TX flow rules need to be inserted manually
> by the application.
> 
> Signed-off-by: Bing Zhao <bingz@nvidia.com>
> Acked-by: Ori Kam <orika@nvidia.com>
> ---
> v4: squash document update and more info for the two new attributes
> v2: optimize the structure and remove unused macros
> ---

Acked-by: Thomas Monjalon <thomas@monjalon.net>

Minor comments below.

>  struct rte_eth_hairpin_conf {
> -	uint16_t peer_count; /**< The number of peers. */
> +	uint32_t peer_count:16; /**< The number of peers. */
> +
> +	/**
> +	 * Explicit TX flow rule mode. One hairpin pair of queues should have
> +	 * the same attribute. The actual support depends on the PMD.

The second sentence should be on a separate line.

About the third sentence, implementation is always PMD-specific.
PMD will reject the not supported conf, as usual.
I think this comment is not needed in the API description.

> +	 *
> +	 * - When set, the user should be responsible for inserting the hairpin
> +	 *   TX part flows and removing them.
> +	 * - When clear, the PMD will try to handle the TX part of the flows,
> +	 *   e.g., by splitting one flow into two parts.
> +	 */
> +	uint32_t tx_explicit:1;
> +
> +	/**
> +	 * Manually bind hairpin queues. One hairpin pair of queues should have
> +	 * the same attribute. The actual support depends on the PMD.

Same here

> +	 *
> +	 * - When set, to enable hairpin, the user should call the hairpin bind
> +	 *   API after all the queues are set up properly and the ports are
> +	 *   started. Also, the hairpin unbind API should be called accordingly
> +	 *   before stopping a port that with hairpin configured.
> +	 * - When clear, the PMD will try to enable the hairpin with the queues
> +	 *   configured automatically during port start.
> +	 */
> +	uint32_t manual_bind:1;
> +	uint32_t reserved:14; /**< Reserved bits. */
>  	struct rte_eth_hairpin_peer peers[RTE_ETH_MAX_HAIRPIN_PEERS];
>  };