From: Yuval Mintz <yuvalm@mellanox.com>
Date: Wed, 10 Jan 2018 11:42:43 +0100
Subject: mlxsw: pci: Wait after reset before accessing HW
Patch-mainline: v4.15-rc8
Git-commit: 8e033a93b37f37aa9fca71a370a895155320af60
References: bsc#1112374

After performing reset driver polls on HW indication until learning
that the reset is done, but immediately after reset the device becomes
unresponsive which might lead to completion timeout on the first read.

Wait for 100ms before starting the polling.

Fixes: 233fa44bd67a ("mlxsw: pci: Implement reset done check")
Signed-off-by: Yuval Mintz <yuvalm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/pci.c    |    7 ++++++-
 drivers/net/ethernet/mellanox/mlxsw/pci_hw.h |    1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/pci.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c
@@ -1643,7 +1643,12 @@ static int mlxsw_pci_sw_reset(struct mlx
 		return 0;
 	}
 
-	wmb(); /* reset needs to be written before we read control register */
+	/* Reset needs to be written before we read control register, and
+	 * we must wait for the HW to become responsive once again
+	 */
+	wmb();
+	msleep(MLXSW_PCI_SW_RESET_WAIT_MSECS);
+
 	end = jiffies + msecs_to_jiffies(MLXSW_PCI_SW_RESET_TIMEOUT_MSECS);
 	do {
 		u32 val = mlxsw_pci_read32(mlxsw_pci, FW_READY);
--- a/drivers/net/ethernet/mellanox/mlxsw/pci_hw.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/pci_hw.h
@@ -59,6 +59,7 @@
 #define MLXSW_PCI_SW_RESET			0xF0010
 #define MLXSW_PCI_SW_RESET_RST_BIT		BIT(0)
 #define MLXSW_PCI_SW_RESET_TIMEOUT_MSECS	5000
+#define MLXSW_PCI_SW_RESET_WAIT_MSECS		100
 #define MLXSW_PCI_FW_READY			0xA1844
 #define MLXSW_PCI_FW_READY_MASK			0xFFFF
 #define MLXSW_PCI_FW_READY_MAGIC		0x5E