[RFC v2 1/1] dmadev: support priority configuration

[Vamsi Krishna <vattunuru@marvell.com>]

From: Vamsi Attunuru <vattunuru@marvell.com>

Some DMA controllers offer the ability to configure priority level
for the hardware command queues, allowing for the prioritization of
DMA command execution based on queue importance.

This patch introduces the necessary fields in the dmadev structures to
retrieve information about the hardware-supported priority levels and to
enable priority configuration from the application.

Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
Signed-off-by: Amit Prakash Shukla <amitprakashs@marvell.com>
---
V2 changes:
* Reverted removed text from release_24_11.rst

V1 changes:
* Added trace support
* Added new capability flag

Deprecation notice:
https://patches.dpdk.org/project/dpdk/patch/20240730144612.2132848-1-amitprakashs@marvell.com/

* Assuming we do not anticipate any advanced scheduling schemes for dmadev queues,
  this RFC is intended to support a strict priority scheme.

 doc/guides/rel_notes/release_24_11.rst |  8 ++++++++
 lib/dmadev/rte_dmadev.c                | 15 +++++++++++++++
 lib/dmadev/rte_dmadev.h                | 21 +++++++++++++++++++++
 lib/dmadev/rte_dmadev_trace.h          |  2 ++
 4 files changed, 46 insertions(+)

diff --git a/doc/guides/rel_notes/release_24_11.rst b/doc/guides/rel_notes/release_24_11.rst
index 0ff70d9057..fc3610deff 100644
--- a/doc/guides/rel_notes/release_24_11.rst
+++ b/doc/guides/rel_notes/release_24_11.rst
@@ -55,6 +55,11 @@ New Features
      Also, make sure to start the actual text at the margin.
      =======================================================
 
+* **Added strict priority capability flag in dmadev.**
+
+  Added new capability flag ``RTE_DMA_CAPA_PRI_POLICY_SP`` to check if the
+  DMA device supports assigning fixed priority to its channels, allowing
+  for better control over resource allocation and scheduling.
 
 Removed Items
 -------------
@@ -100,6 +105,9 @@ ABI Changes
    Also, make sure to start the actual text at the margin.
    =======================================================
 
+* dmadev: Added ``nb_priorities`` field to ``rte_dma_info`` structure and
+  ``priority`` field to ``rte_dma_conf`` structure to get device supported
+  priority levels and configure required priority from the application.
 
 Known Issues
 ------------
diff --git a/lib/dmadev/rte_dmadev.c b/lib/dmadev/rte_dmadev.c
index 845727210f..3d9063dee3 100644
--- a/lib/dmadev/rte_dmadev.c
+++ b/lib/dmadev/rte_dmadev.c
@@ -497,6 +497,21 @@ rte_dma_configure(int16_t dev_id, const struct rte_dma_conf *dev_conf)
 		return -EINVAL;
 	}
 
+	if (dev_conf->priority && !(dev_info.dev_capa & RTE_DMA_CAPA_PRI_POLICY_SP)) {
+		RTE_DMA_LOG(ERR, "Device %d don't support prioritization", dev_id);
+		return -EINVAL;
+	}
+
+	if (dev_info.nb_priorities == 1) {
+		RTE_DMA_LOG(ERR, "Device %d must support more than 1 priority, or else 0", dev_id);
+		return -EINVAL;
+	}
+
+	if (dev_info.nb_priorities && (dev_conf->priority >= dev_info.nb_priorities)) {
+		RTE_DMA_LOG(ERR, "Device %d configure invalid priority", dev_id);
+		return -EINVAL;
+	}
+
 	if (*dev->dev_ops->dev_configure == NULL)
 		return -ENOTSUP;
 	ret = (*dev->dev_ops->dev_configure)(dev, dev_conf,
diff --git a/lib/dmadev/rte_dmadev.h b/lib/dmadev/rte_dmadev.h
index 5474a5281d..e5f730c327 100644
--- a/lib/dmadev/rte_dmadev.h
+++ b/lib/dmadev/rte_dmadev.h
@@ -268,6 +268,16 @@ int16_t rte_dma_next_dev(int16_t start_dev_id);
 #define RTE_DMA_CAPA_OPS_COPY_SG	RTE_BIT64(33)
 /** Support fill operation. */
 #define RTE_DMA_CAPA_OPS_FILL		RTE_BIT64(34)
+/** Support strict prioritization at DMA HW channel level
+ *
+ * If device supports HW channel prioritization then application could
+ * assign fixed priority to the DMA HW channel using 'priority' field in
+ * struct rte_dma_conf. Number of supported priority levels will be known
+ * from 'nb_priorities' field in struct rte_dma_info.
+ *
+ * DMA devices which support prioritization can advertise this capability.
+ */
+#define RTE_DMA_CAPA_PRI_POLICY_SP	RTE_BIT64(35)
 /**@}*/
 
 /**
@@ -297,6 +307,10 @@ struct rte_dma_info {
 	int16_t numa_node;
 	/** Number of virtual DMA channel configured. */
 	uint16_t nb_vchans;
+	/** Number of priority levels (must be > 1), if supported by DMA HW channel.
+	 * 0 otherwise.
+	 */
+	uint16_t nb_priorities;
 };
 
 /**
@@ -332,6 +346,13 @@ struct rte_dma_conf {
 	 * @see RTE_DMA_CAPA_SILENT
 	 */
 	bool enable_silent;
+	/* The priority of the DMA HW channel.
+	 * This value cannot be greater than or equal to the field 'nb_priorities'
+	 * of struct rte_dma_info which get from rte_dma_info_get().
+	 * Among the values between '0' and 'nb_priorities - 1', lowest value
+	 * indicates higher priority and vice-versa.
+	 */
+	uint16_t priority;
 };
 
 /**
diff --git a/lib/dmadev/rte_dmadev_trace.h b/lib/dmadev/rte_dmadev_trace.h
index e55c4c6091..be089c065c 100644
--- a/lib/dmadev/rte_dmadev_trace.h
+++ b/lib/dmadev/rte_dmadev_trace.h
@@ -35,6 +35,7 @@ RTE_TRACE_POINT(
 	rte_trace_point_emit_u16(dev_info->max_sges);
 	rte_trace_point_emit_i16(dev_info->numa_node);
 	rte_trace_point_emit_u16(dev_info->nb_vchans);
+	rte_trace_point_emit_u16(dev_info->nb_priorities);
 )
 
 RTE_TRACE_POINT(
@@ -48,6 +49,7 @@ RTE_TRACE_POINT(
 	int enable_silent = (int)dev_conf->enable_silent;
 	rte_trace_point_emit_i16(dev_id);
 	rte_trace_point_emit_u16(dev_conf->nb_vchans);
+	rte_trace_point_emit_u16(dev_conf->priority);
 	rte_trace_point_emit_int(enable_silent);
 	rte_trace_point_emit_int(ret);
 )
-- 
2.34.1