From: Ido Schimmel <idosch@nvidia.com>
Date: Tue, 17 Nov 2020 19:33:52 +0200
Subject: mlxsw: core: Use variable timeout for EMAD retries
Patch-mainline: v5.10-rc5
Git-commit: 1f492eab67bced119a0ac7db75ef2047e29a30c6
References: git-fixes

The driver sends Ethernet Management Datagram (EMAD) packets to the
device for configuration purposes and waits for up to 200ms for a reply.
A request is retried up to 5 times.

When the system is under heavy load, replies are not always processed in
time and EMAD transactions fail.

Make the process more robust to such delays by using exponential
backoff. First wait for up to 200ms, then retransmit and wait for up to
400ms and so on.

Fixes: caf7297e7ab5 ("mlxsw: core: Introduce support for asynchronous EMAD register access")
Reported-by: Denis Yulevich <denisyu@nvidia.com>
Tested-by: Denis Yulevich <denisyu@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -557,7 +557,8 @@ static void mlxsw_emad_trans_timeout_sch
 	if (trans->core->fw_flash_in_progress)
 		timeout = msecs_to_jiffies(MLXSW_EMAD_TIMEOUT_DURING_FW_FLASH_MS);
 
-	queue_delayed_work(trans->core->emad_wq, &trans->timeout_dw, timeout);
+	queue_delayed_work(trans->core->emad_wq, &trans->timeout_dw,
+			   timeout << trans->retries);
 }
 
 static int mlxsw_emad_transmit(struct mlxsw_core *mlxsw_core,