Re: [PATCH v2 08/11] eventdev: improve doxygen comments on config fns

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Jan 23, 2024 at 11:00:50AM +0100, Mattias Rönnblom wrote:
> On 2024-01-19 18:43, Bruce Richardson wrote:
> > Improve the documentation text for the configuration functions and
> > structures for configuring an eventdev, as well as ports and queues.
> > Clarify text where possible, and ensure references come through as links
> > in the html output.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> >   lib/eventdev/rte_eventdev.h | 196 ++++++++++++++++++++++++------------
> >   1 file changed, 130 insertions(+), 66 deletions(-)
> > 
> > diff --git a/lib/eventdev/rte_eventdev.h b/lib/eventdev/rte_eventdev.h
> > index 3b8f5b8101..1fda8a5a13 100644
> > --- a/lib/eventdev/rte_eventdev.h
> > +++ b/lib/eventdev/rte_eventdev.h
> > @@ -676,12 +676,14 @@ struct rte_event_dev_config {
> >   /**
> >    * Configure an event device.
> >    *
> > - * This function must be invoked first before any other function in the
> > - * API. This function can also be re-invoked when a device is in the
> > - * stopped state.
> > + * This function must be invoked before any other configuration function in the
> > + * API, when preparing an event device for application use.
> > + * This function can also be re-invoked when a device is in the stopped state.
> >    *
> > - * The caller may use rte_event_dev_info_get() to get the capability of each
> > - * resources available for this event device.
> > + * The caller should use rte_event_dev_info_get() to get the capabilities and
> > + * resource limits for this event device before calling this API.
> 
> "should" -> "may". If you know the limitations by other means, that's fine
> too.
> 

I think I'll keep it as "should", since it's strongly recommended. "Must"
would be incorrect, since it's not mandatory, but I think "may" is too
week.

> > + * Many values in the dev_conf input parameter are subject to limits given
> > + * in the device information returned from rte_event_dev_info_get().
> >    *
> >    * @param dev_id
> >    *   The identifier of the device to configure.
> > @@ -691,6 +693,9 @@ struct rte_event_dev_config {
> >    * @return
> >    *   - 0: Success, device configured.
> >    *   - <0: Error code returned by the driver configuration function.
> > + *     - -ENOTSUP - device does not support configuration
> > + *     - -EINVAL  - invalid input parameter
> > + *     - -EBUSY   - device has already been started
> >    */
> >   int
> >   rte_event_dev_configure(uint8_t dev_id,
> > @@ -700,14 +705,33 @@ rte_event_dev_configure(uint8_t dev_id,
> >   /* Event queue configuration bitmap flags */
> >   #define RTE_EVENT_QUEUE_CFG_ALL_TYPES          (1ULL << 0)
> > -/**< Allow ATOMIC,ORDERED,PARALLEL schedule type enqueue
> > +/**< Allow events with schedule types ATOMIC, ORDERED, and PARALLEL to be enqueued to this queue.
> > + * The scheduling type to be used is that specified in each individual event.
> > + * This flag can only be set when configuring queues on devices reporting the
> > + * @ref RTE_EVENT_DEV_CAP_QUEUE_ALL_TYPES capability.
> >    *
> > + * Without this flag, only events with the specific scheduling type configured at queue setup
> > + * can be sent to the queue.
> > + *
> > + * @see RTE_EVENT_DEV_CAP_QUEUE_ALL_TYPES
> >    * @see RTE_SCHED_TYPE_ORDERED, RTE_SCHED_TYPE_ATOMIC, RTE_SCHED_TYPE_PARALLEL
> >    * @see rte_event_enqueue_burst()
> >    */
> >   #define RTE_EVENT_QUEUE_CFG_SINGLE_LINK        (1ULL << 1)
> >   /**< This event queue links only to a single event port.
> > - *
> > + * No load-balancing of events is performed, as all events
> > + * sent to this queue end up at the same event port.
> > + * The number of queues on which this flag is to be set must be
> > + * configured at device configuration time, by setting
> > + * @ref rte_event_dev_config.nb_single_link_event_port_queues
> > + * parameter appropriately.
> > + *
> > + * This flag serves as a hint only, any devices without specific
> > + * support for single-link queues can fall-back automatically to
> > + * using regular queues with a single destination port.
> > + *
> > + *  @see rte_event_dev_info.max_single_link_event_port_queue_pairs
> > + *  @see rte_event_dev_config.nb_single_link_event_port_queues
> >    *  @see rte_event_port_setup(), rte_event_port_link()
> >    */
> > @@ -715,56 +739,75 @@ rte_event_dev_configure(uint8_t dev_id,
> >   struct rte_event_queue_conf {
> >   	uint32_t nb_atomic_flows;
> >   	/**< The maximum number of active flows this queue can track at any
> > -	 * given time. If the queue is configured for atomic scheduling (by
> > -	 * applying the RTE_EVENT_QUEUE_CFG_ALL_TYPES flag to event_queue_cfg
> > -	 * or RTE_SCHED_TYPE_ATOMIC flag to schedule_type), then the
> > -	 * value must be in the range of [1, nb_event_queue_flows], which was
> > -	 * previously provided in rte_event_dev_configure().
> > +	 * given time.
> > +	 *
> > +	 * If the queue is configured for atomic scheduling (by
> > +	 * applying the @ref RTE_EVENT_QUEUE_CFG_ALL_TYPES flag to
> > +	 * @ref rte_event_queue_conf.event_queue_cfg
> > +	 * or @ref RTE_SCHED_TYPE_ATOMIC flag to @ref rte_event_queue_conf.schedule_type), then the
> > +	 * value must be in the range of [1, @ref rte_event_dev_config.nb_event_queue_flows],
> > +	 * which was previously provided in rte_event_dev_configure().
> > +	 *
> > +	 * If the queue is not configured for atomic scheduling this value is ignored.
> >   	 */
> >   	uint32_t nb_atomic_order_sequences;
> >   	/**< The maximum number of outstanding events waiting to be
> >   	 * reordered by this queue. In other words, the number of entries in
> >   	 * this queue’s reorder buffer.When the number of events in the
> >   	 * reorder buffer reaches to *nb_atomic_order_sequences* then the
> > -	 * scheduler cannot schedule the events from this queue and invalid
> > -	 * event will be returned from dequeue until one or more entries are
> > +	 * scheduler cannot schedule the events from this queue and no
> > +	 * events will be returned from dequeue until one or more entries are
> >   	 * freed up/released.
> > +	 *
> >   	 * If the queue is configured for ordered scheduling (by applying the
> > -	 * RTE_EVENT_QUEUE_CFG_ALL_TYPES flag to event_queue_cfg or
> > -	 * RTE_SCHED_TYPE_ORDERED flag to schedule_type), then the value must
> > -	 * be in the range of [1, nb_event_queue_flows], which was
> > +	 * @ref RTE_EVENT_QUEUE_CFG_ALL_TYPES flag to @ref rte_event_queue_conf.event_queue_cfg or
> > +	 * @ref RTE_SCHED_TYPE_ORDERED flag to @ref rte_event_queue_conf.schedule_type),
> > +	 * then the value must be in the range of
> > +	 * [1, @ref rte_event_dev_config.nb_event_queue_flows], which was
> >   	 * previously supplied to rte_event_dev_configure().
> > +	 *
> > +	 * If the queue is not configured for ordered scheduling, then this value is ignored
> >   	 */
> >   	uint32_t event_queue_cfg;
> >   	/**< Queue cfg flags(EVENT_QUEUE_CFG_) */
> >   	uint8_t schedule_type;
> >   	/**< Queue schedule type(RTE_SCHED_TYPE_*).
> > -	 * Valid when RTE_EVENT_QUEUE_CFG_ALL_TYPES bit is not set in
> > -	 * event_queue_cfg.
> > +	 * Valid when @ref RTE_EVENT_QUEUE_CFG_ALL_TYPES flag is not set in
> > +	 * @ref rte_event_queue_conf.event_queue_cfg.
> > +	 *
> > +	 * If the @ref RTE_EVENT_QUEUE_CFG_ALL_TYPES flag is set, then this field is ignored.
> > +	 *
> > +	 * @see RTE_SCHED_TYPE_ORDERED, RTE_SCHED_TYPE_ATOMIC, RTE_SCHED_TYPE_PARALLEL
> >   	 */
> >   	uint8_t priority;
> >   	/**< Priority for this event queue relative to other event queues.
> >   	 * The requested priority should in the range of
> > -	 * [RTE_EVENT_DEV_PRIORITY_HIGHEST, RTE_EVENT_DEV_PRIORITY_LOWEST].
> > +	 * [@ref RTE_EVENT_DEV_PRIORITY_HIGHEST, @ref RTE_EVENT_DEV_PRIORITY_LOWEST].
> >   	 * The implementation shall normalize the requested priority to
> >   	 * event device supported priority value.
> > -	 * Valid when the device has RTE_EVENT_DEV_CAP_QUEUE_QOS capability
> > +	 *
> > +	 * Valid when the device has @ref RTE_EVENT_DEV_CAP_QUEUE_QOS capability,
> > +	 * ignored otherwise
> >   	 */
> >   	uint8_t weight;
> >   	/**< Weight of the event queue relative to other event queues.
> >   	 * The requested weight should be in the range of
> > -	 * [RTE_EVENT_DEV_WEIGHT_HIGHEST, RTE_EVENT_DEV_WEIGHT_LOWEST].
> > +	 * [@ref RTE_EVENT_QUEUE_WEIGHT_HIGHEST, @ref RTE_EVENT_QUEUE_WEIGHT_LOWEST].
> >   	 * The implementation shall normalize the requested weight to event
> >   	 * device supported weight value.
> > -	 * Valid when the device has RTE_EVENT_DEV_CAP_QUEUE_QOS capability.
> > +	 *
> > +	 * Valid when the device has @ref RTE_EVENT_DEV_CAP_QUEUE_QOS capability,
> > +	 * ignored otherwise.
> >   	 */
> >   	uint8_t affinity;
> >   	/**< Affinity of the event queue relative to other event queues.
> >   	 * The requested affinity should be in the range of
> > -	 * [RTE_EVENT_DEV_AFFINITY_HIGHEST, RTE_EVENT_DEV_AFFINITY_LOWEST].
> > +	 * [@ref RTE_EVENT_QUEUE_AFFINITY_HIGHEST, @ref RTE_EVENT_QUEUE_AFFINITY_LOWEST].
> >   	 * The implementation shall normalize the requested affinity to event
> >   	 * device supported affinity value.
> > -	 * Valid when the device has RTE_EVENT_DEV_CAP_QUEUE_QOS capability.
> > +	 *
> > +	 * Valid when the device has @ref RTE_EVENT_DEV_CAP_QUEUE_QOS capability,
> > +	 * ignored otherwise.
> >   	 */
> >   };
> > @@ -779,7 +822,7 @@ struct rte_event_queue_conf {
> >    *   The identifier of the device.
> >    * @param queue_id
> >    *   The index of the event queue to get the configuration information.
> > - *   The value must be in the range [0, nb_event_queues - 1]
> > + *   The value must be in the range [0, @ref rte_event_dev_config.nb_event_queues - 1]
> 
> The value must be < @ref rte_event_dev_config.nb_event_queues.
> 
> It's an unsigned type, so no need to specify a lower bound.
> 

Ok. This probably applies in many places throughout the whole header file.

> >    *   previously supplied to rte_event_dev_configure().
> >    * @param[out] queue_conf
> >    *   The pointer to the default event queue configuration data.
> > @@ -800,7 +843,8 @@ rte_event_queue_default_conf_get(uint8_t dev_id, uint8_t queue_id,
> >    *   The identifier of the device.
> >    * @param queue_id
> >    *   The index of the event queue to setup. The value must be in the range
> > - *   [0, nb_event_queues - 1] previously supplied to rte_event_dev_configure().
> > + *   [0, @ref rte_event_dev_config.nb_event_queues - 1] previously supplied to
> > + *   rte_event_dev_configure().
> >    * @param queue_conf
> >    *   The pointer to the configuration data to be used for the event queue.
> >    *   NULL value is allowed, in which case default configuration	used.
> > @@ -816,43 +860,44 @@ rte_event_queue_setup(uint8_t dev_id, uint8_t queue_id,
> >   		      const struct rte_event_queue_conf *queue_conf);
> >   /**
> > - * The priority of the queue.
> > + * Queue attribute id for the priority of the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_PRIORITY 0
> >   /**
> > - * The number of atomic flows configured for the queue.
> > + * Queue attribute id for the number of atomic flows configured for the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_NB_ATOMIC_FLOWS 1
> >   /**
> > - * The number of atomic order sequences configured for the queue.
> > + * Queue attribute id for the number of atomic order sequences configured for the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_NB_ATOMIC_ORDER_SEQUENCES 2
> >   /**
> > - * The cfg flags for the queue.
> > + * Queue attribute id for the cfg flags for the queue.
> 
> "cfg" -> "configuration"?
> 
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_EVENT_QUEUE_CFG 3
> >   /**
> > - * The schedule type of the queue.
> > + * Queue attribute id for the schedule type of the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_SCHEDULE_TYPE 4
> >   /**
> > - * The weight of the queue.
> > + * Queue attribute id for the weight of the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_WEIGHT 5
> >   /**
> > - * Affinity of the queue.
> > + * Queue attribute id for the affinity of the queue.
> >    */
> >   #define RTE_EVENT_QUEUE_ATTR_AFFINITY 6
> >   /**
> > - * Get an attribute from a queue.
> > + * Get an attribute or property of an event queue.
> 
> What is the difference between property and attribute here?
> 

Good question. Not sure what I had in mind here. I'll revert in v3, I
think.

> >    *
> >    * @param dev_id
> > - *   Eventdev id
> > + *   The identifier of the device.
> >    * @param queue_id
> > - *   Eventdev queue id
> > + *   The index of the event queue to query. The value must be in the range
> > + *   [0, nb_event_queues - 1] previously supplied to rte_event_dev_configure().
> >    * @param attr_id
> > - *   The attribute ID to retrieve
> > + *   The attribute ID to retrieve (RTE_EVENT_QUEUE_ATTR_*)
> >    * @param[out] attr_value
> >    *   A pointer that will be filled in with the attribute value if successful
> >    *
> > @@ -861,8 +906,8 @@ rte_event_queue_setup(uint8_t dev_id, uint8_t queue_id,
> >    *   - -EINVAL: invalid device, queue or attr_id provided, or attr_value was
> >    *		NULL
> >    *   - -EOVERFLOW: returned when attr_id is set to
> > - *   RTE_EVENT_QUEUE_ATTR_SCHEDULE_TYPE and event_queue_cfg is set to
> > - *   RTE_EVENT_QUEUE_CFG_ALL_TYPES
> > + *   @ref RTE_EVENT_QUEUE_ATTR_SCHEDULE_TYPE and @ref RTE_EVENT_QUEUE_CFG_ALL_TYPES is
> > + *   set in the queue configuration flags.
> >    */
> >   int
> >   rte_event_queue_attr_get(uint8_t dev_id, uint8_t queue_id, uint32_t attr_id,
> > @@ -872,11 +917,13 @@ rte_event_queue_attr_get(uint8_t dev_id, uint8_t queue_id, uint32_t attr_id,
> >    * Set an event queue attribute.
> >    *
> >    * @param dev_id
> > - *   Eventdev id
> > + *   The identifier of the device.
> >    * @param queue_id
> > - *   Eventdev queue id
> > + *   The index of the event queue to configure. The value must be in the range
> > + *   [0, @ref rte_event_dev_config.nb_event_queues - 1] previously
> > + *   supplied to rte_event_dev_configure().
> >    * @param attr_id
> > - *   The attribute ID to set
> > + *   The attribute ID to set (RTE_EVENT_QUEUE_ATTR_*)
> >    * @param attr_value
> >    *   The attribute value to set
> >    *
> > @@ -902,7 +949,10 @@ rte_event_queue_attr_set(uint8_t dev_id, uint8_t queue_id, uint32_t attr_id,
> >    */
> >   #define RTE_EVENT_PORT_CFG_SINGLE_LINK         (1ULL << 1)
> >   /**< This event port links only to a single event queue.
> > + * The queue it links with should be similarly configured with the
> > + * @ref RTE_EVENT_QUEUE_CFG_SINGLE_LINK flag.
> >    *
> > + *  @see RTE_EVENT_QUEUE_CFG_SINGLE_LINK
> >    *  @see rte_event_port_setup(), rte_event_port_link()
> >    */
> >   #define RTE_EVENT_PORT_CFG_HINT_PRODUCER       (1ULL << 2)
> > @@ -918,7 +968,7 @@ rte_event_queue_attr_set(uint8_t dev_id, uint8_t queue_id, uint32_t attr_id,
> >   #define RTE_EVENT_PORT_CFG_HINT_CONSUMER       (1ULL << 3)
> >   /**< Hint that this event port will primarily dequeue events from the system.
> >    * A PMD can optimize its internal workings by assuming that this port is
> > - * primarily going to consume events, and not enqueue FORWARD or RELEASE
> > + * primarily going to consume events, and not enqueue NEW or FORWARD
> >    * events.
> >    *
> >    * Note that this flag is only a hint, so PMDs must operate under the
> > @@ -944,48 +994,55 @@ struct rte_event_port_conf {
> >   	/**< A backpressure threshold for new event enqueues on this port.
> >   	 * Use for *closed system* event dev where event capacity is limited,
> >   	 * and cannot exceed the capacity of the event dev.
> > +	 *
> >   	 * Configuring ports with different thresholds can make higher priority
> >   	 * traffic less likely to  be backpressured.
> >   	 * For example, a port used to inject NIC Rx packets into the event dev
> >   	 * can have a lower threshold so as not to overwhelm the device,
> >   	 * while ports used for worker pools can have a higher threshold.
> > -	 * This value cannot exceed the *nb_events_limit*
> > +	 * This value cannot exceed the @ref rte_event_dev_config.nb_events_limit value
> >   	 * which was previously supplied to rte_event_dev_configure().
> > -	 * This should be set to '-1' for *open system*.
> > +	 *
> > +	 * This should be set to '-1' for *open system*, i.e when
> > +	 * @ref rte_event_dev_info.max_num_events == -1.
> >   	 */
> >   	uint16_t dequeue_depth;
> > -	/**< Configure number of bulk dequeues for this event port.
> > -	 * This value cannot exceed the *nb_event_port_dequeue_depth*
> > -	 * which previously supplied to rte_event_dev_configure().
> > -	 * Ignored when device is not RTE_EVENT_DEV_CAP_BURST_MODE capable.
> > +	/**< Configure the maximum size of burst dequeues for this event port.
> > +	 * This value cannot exceed the @ref rte_event_dev_config.nb_event_port_dequeue_depth value
> > +	 * which was previously supplied to rte_event_dev_configure().
> > +	 *
> > +	 * Ignored when device does not support the @ref RTE_EVENT_DEV_CAP_BURST_MODE capability.
> >   	 */
> >   	uint16_t enqueue_depth;
> > -	/**< Configure number of bulk enqueues for this event port.
> > -	 * This value cannot exceed the *nb_event_port_enqueue_depth*
> > -	 * which previously supplied to rte_event_dev_configure().
> > -	 * Ignored when device is not RTE_EVENT_DEV_CAP_BURST_MODE capable.
> > +	/**< Configure the maximum size of burst enqueues to this event port.
> > +	 * This value cannot exceed the @ref rte_event_dev_config.nb_event_port_enqueue_depth value
> > +	 * which was previously supplied to rte_event_dev_configure().
> > +	 *
> > +	 * Ignored when device does not support the @ref RTE_EVENT_DEV_CAP_BURST_MODE capability.
> >   	 */
> > -	uint32_t event_port_cfg; /**< Port cfg flags(EVENT_PORT_CFG_) */
> > +	uint32_t event_port_cfg; /**< Port configuration flags(EVENT_PORT_CFG_) */
> >   };
> >   /**
> >    * Retrieve the default configuration information of an event port designated
> >    * by its *port_id* from the event driver for an event device.
> >    *
> > - * This function intended to be used in conjunction with rte_event_port_setup()
> > - * where caller needs to set up the port by overriding few default values.
> > + * This function is intended to be used in conjunction with rte_event_port_setup()
> > + * where the caller can set up the port by just overriding few default values.
> >    *
> >    * @param dev_id
> >    *   The identifier of the device.
> >    * @param port_id
> >    *   The index of the event port to get the configuration information.
> > - *   The value must be in the range [0, nb_event_ports - 1]
> > + *   The value must be in the range [0, @ref rte_event_dev_config.nb_event_ports - 1]
> >    *   previously supplied to rte_event_dev_configure().
> >    * @param[out] port_conf
> > - *   The pointer to the default event port configuration data
> > + *   The pointer to a structure to store the default event port configuration data.
> >    * @return
> >    *   - 0: Success, driver updates the default event port configuration data.
> >    *   - <0: Error code returned by the driver info get function.
> > + *      - -EINVAL - invalid input parameter
> > + *      - -ENOTSUP - function is not supported for this device
> >    *
> >    * @see rte_event_port_setup()
> >    */
> > @@ -1000,18 +1057,24 @@ rte_event_port_default_conf_get(uint8_t dev_id, uint8_t port_id,
> >    *   The identifier of the device.
> >    * @param port_id
> >    *   The index of the event port to setup. The value must be in the range
> > - *   [0, nb_event_ports - 1] previously supplied to rte_event_dev_configure().
> > + *   [0, @ref rte_event_dev_config.nb_event_ports - 1] previously supplied to
> > + *   rte_event_dev_configure().
> >    * @param port_conf
> > - *   The pointer to the configuration data to be used for the queue.
> > - *   NULL value is allowed, in which case default configuration	used.
> > + *   The pointer to the configuration data to be used for the port.
> > + *   NULL value is allowed, in which case the default configuration is used.
> >    *
> >    * @see rte_event_port_default_conf_get()
> >    *
> >    * @return
> >    *   - 0: Success, event port correctly set up.
> >    *   - <0: Port configuration failed
> > - *   - (-EDQUOT) Quota exceeded(Application tried to link the queue configured
> > - *   with RTE_EVENT_QUEUE_CFG_SINGLE_LINK to more than one event ports)
> > + *     - -EINVAL - Invalid input parameter
> > + *     - -EBUSY - Port already started
> > + *     - -ENOTSUP - Function not supported on this device, or a NULL pointer passed
> > + *        as the port_conf parameter, and no default configuration function available
> > + *        for this device.
> > + *     - -EDQUOT - Application tried to link a queue configured
> 
> "." for each bullet?
> 
Ideally, yes. I'll try and keep this consistent as I make changes, but it's
not going to be top of my worry-about list!

thanks again for the reviews.

/Bruce