mlxsw: pci: Wait after reset before accessing HW

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>

2 files changed, 7 insertions, 1 deletions

diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c
index 23f7d828cf67..6ef20e5cc77d 100644
--- 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 mlxsw_pci *mlxsw_pci,
                 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);
diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci_hw.h b/drivers/net/ethernet/mellanox/mlxsw/pci_hw.h
index a6441208e9d9..fb082ad21b00 100644
--- 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