From: Huy Nguyen <huyn@mellanox.com>
Date: Fri, 6 Sep 2019 09:28:46 -0500
Subject: net/mlx5e: Query global pause state before setting prio2buffer
Patch-mainline: v5.5-rc1
Git-commit: 73e6551699a32fac703ceea09214d6580edcf2d5
References: bsc#1103990 FATE#326006

When the user changes prio2buffer mapping while global pause is
enabled, mlx5 driver incorrectly sets all active buffers
(buffer that has at least one priority mapped) to lossy.

Solution:
If global pause is enabled, set all the active buffers to lossless
in prio2buffer command.
Also, add error message when buffer size is not enough to meet
xoff threshold.

Fixes: 0696d60853d5 ("net/mlx5e: Receive buffer configuration")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c |   27 +++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c
@@ -155,8 +155,11 @@ static int update_xoff_threshold(struct
 		}
 
 		if (port_buffer->buffer[i].size <
-		    (xoff + max_mtu + (1 << MLX5E_BUFFER_CELL_SHIFT)))
+		    (xoff + max_mtu + (1 << MLX5E_BUFFER_CELL_SHIFT))) {
+			pr_err("buffer_size[%d]=%d is not enough for lossless buffer\n",
+			       i, port_buffer->buffer[i].size);
 			return -ENOMEM;
+		}
 
 		port_buffer->buffer[i].xoff = port_buffer->buffer[i].size - xoff;
 		port_buffer->buffer[i].xon  =
@@ -232,6 +235,26 @@ static int update_buffer_lossy(unsigned
 	return 0;
 }
 
+static int fill_pfc_en(struct mlx5_core_dev *mdev, u8 *pfc_en)
+{
+	u32 g_rx_pause, g_tx_pause;
+	int err;
+
+	err = mlx5_query_port_pause(mdev, &g_rx_pause, &g_tx_pause);
+	if (err)
+		return err;
+
+	/* If global pause enabled, set all active buffers to lossless.
+	 * Otherwise, check PFC setting.
+	 */
+	if (g_rx_pause || g_tx_pause)
+		*pfc_en = 0xff;
+	else
+		err = mlx5_query_port_pfc(mdev, pfc_en, NULL);
+
+	return err;
+}
+
 #define MINIMUM_MAX_MTU 9216
 int mlx5e_port_manual_buffer_config(struct mlx5e_priv *priv,
 				    u32 change, unsigned int mtu,
@@ -277,7 +300,7 @@ int mlx5e_port_manual_buffer_config(stru
 
 	if (change & MLX5E_PORT_BUFFER_PRIO2BUFFER) {
 		update_prio2buffer = true;
-		err = mlx5_query_port_pfc(priv->mdev, &curr_pfc_en, NULL);
+		err = fill_pfc_en(priv->mdev, &curr_pfc_en);
 		if (err)
 			return err;