From: Yamin Friedman <yaminf@mellanox.com>
Date: Mon, 7 Oct 2019 16:59:33 +0300
Subject: RDMA/mlx5: Add capability for max sge to get optimized performance
Patch-mainline: v5.5-rc1
Git-commit: 366090564b812453f531051129b82b63dad8f38b
References: jsc#SLE-8446

Allows the IB device to provide a value of maximum scatter gather entries
per RDMA READ.

In certain cases it may be preferable for a device to perform UMR memory
registration rather than have many scatter entries in a single RDMA READ.
This provides a significant performance increase in devices capable of
using different memory registration schemes based on the number of scatter
gather entries. This general capability allows each device vendor to fine
tune when it is better to use memory registration.

Link: https://lore.kernel.org/r/20191007135933.12483-4-leon@kernel.org
Signed-off-by: Yamin Friedman <yaminf@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/hw/mlx5/main.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1011,6 +1011,8 @@ static int mlx5_ib_query_device(struct i
 		1 << MLX5_CAP_GEN(mdev, log_max_klm_list_size);
 	props->max_pi_fast_reg_page_list_len =
 		props->max_fast_reg_page_list_len / 2;
+	props->max_sgl_rd =
+		MLX5_CAP_GEN(mdev, max_sgl_for_optimized_performance);
 	get_atomic_caps_qp(dev, props);
 	props->masked_atomic_cap   = IB_ATOMIC_NONE;
 	props->max_mcast_grp	   = 1 << MLX5_CAP_GEN(mdev, log_max_mcg);