net/mlx5: Let user configure io_eq_size param

Currently, each I/O EQ is taking 128KB of memory. This size
is not needed in all use cases, and is critical with large scale.
Hence, allow user to configure the size of I/O EQs.

For example, to reduce I/O EQ size to 64, execute:
$ devlink dev param set pci/0000:00:0b.0 name io_eq_size value 64 \
              cmode driverinit
$ devlink dev reload pci/0000:00:0b.0
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Documentation/networking/devlink/mlx5.rst

@@ -14,8 +14,12 @@ Parameters
 
    * - Name
      - Mode
+     - Validation
    * - ``enable_roce``
      - driverinit
+   * - ``io_eq_size``
+     - driverinit
+     - The range is between 64 and 4096.
 
 The ``mlx5`` driver also implements the following driver-specific
 parameters.

drivers/net/ethernet/mellanox/mlx5/core/devlink.c

@@ -546,6 +546,13 @@ static int mlx5_devlink_enable_remote_dev_reset_get(struct devlink *devlink, u32
 	return 0;
 }
 
+static int mlx5_devlink_eq_depth_validate(struct devlink *devlink, u32 id,
+					  union devlink_param_value val,
+					  struct netlink_ext_ack *extack)
+{
+	return (val.vu16 >= 64 && val.vu16 <= 4096) ? 0 : -EINVAL;
+}
+
 static const struct devlink_param mlx5_devlink_params[] = {
 	DEVLINK_PARAM_DRIVER(MLX5_DEVLINK_PARAM_ID_FLOW_STEERING_MODE,
 			     "flow_steering_mode", DEVLINK_PARAM_TYPE_STRING,
@@ -570,6 +577,8 @@ static const struct devlink_param mlx5_devlink_params[] = {
 	DEVLINK_PARAM_GENERIC(ENABLE_REMOTE_DEV_RESET, BIT(DEVLINK_PARAM_CMODE_RUNTIME),
 			      mlx5_devlink_enable_remote_dev_reset_get,
 			      mlx5_devlink_enable_remote_dev_reset_set, NULL),
+	DEVLINK_PARAM_GENERIC(IO_EQ_SIZE, BIT(DEVLINK_PARAM_CMODE_DRIVERINIT),
+			      NULL, NULL, mlx5_devlink_eq_depth_validate),
 };
 
 static void mlx5_devlink_set_params_init_values(struct devlink *devlink)
@@ -608,6 +617,11 @@ static void mlx5_devlink_set_params_init_values(struct devlink *devlink)
 						   value);
 	}
 #endif
+
+	value.vu32 = MLX5_COMP_EQ_SIZE;
+	devlink_param_driverinit_value_set(devlink,
+					   DEVLINK_PARAM_GENERIC_ID_IO_EQ_SIZE,
+					   value);
 }
 
 static const struct devlink_param enable_eth_param =

drivers/net/ethernet/mellanox/mlx5/core/eq.c

@@ -19,6 +19,7 @@
 #include "lib/clock.h"
 #include "diag/fw_tracer.h"
 #include "mlx5_irq.h"
+#include "devlink.h"
 
 enum {
 	MLX5_EQE_OWNER_INIT_VAL	= 0x1,
@@ -796,6 +797,21 @@ static void destroy_comp_eqs(struct mlx5_core_dev *dev)
 	}
 }
 
+static u16 comp_eq_depth_devlink_param_get(struct mlx5_core_dev *dev)
+{
+	struct devlink *devlink = priv_to_devlink(dev);
+	union devlink_param_value val;
+	int err;
+
+	err = devlink_param_driverinit_value_get(devlink,
+						 DEVLINK_PARAM_GENERIC_ID_IO_EQ_SIZE,
+						 &val);
+	if (!err)
+		return val.vu32;
+	mlx5_core_dbg(dev, "Failed to get param. using default. err = %d\n", err);
+	return MLX5_COMP_EQ_SIZE;
+}
+
 static int create_comp_eqs(struct mlx5_core_dev *dev)
 {
 	struct mlx5_eq_table *table = dev->priv.eq_table;
@@ -807,7 +823,7 @@ static int create_comp_eqs(struct mlx5_core_dev *dev)
 
 	INIT_LIST_HEAD(&table->comp_eqs_list);
 	ncomp_eqs = table->num_comp_eqs;
-	nent = MLX5_COMP_EQ_SIZE;
+	nent = comp_eq_depth_devlink_param_get(dev);
 	for (i = 0; i < ncomp_eqs; i++) {
 		struct mlx5_eq_param param = {};
 		int vecidx = i;