mlx4_core: Use MOD_STAT_CFG command to get minimal page size

There was a bug in some versions of the mlx4 driver in
mlx4_alloc_fmr(), which hardcoded the minimum acceptable page_shift to
be 12.  However, new ConnectX firmware can support a minimum
page_shift of 9 (log_pg_sz of 9 returned by QUERY_DEV_LIM) -- so with
old drivers, ib_fmr_alloc() would fail for ULPs using the device
minimum when creating FMRs.

To preserve firmware compatibility with released mlx4 drivers, the
firmware will continue to return 12 as before for log_page_sz in
QUERY_DEV_CAP for these drivers.  However, to enable new drivers to
take advantage of the available smaller page size, the mlx4 driver now
first sets the log_pg_sz to the device minimum by setting a
log_page_sz value to 0 via the MOD_STAT_CFG command and then reading
the real minimum via QUERY_DEV_CAP.

Signed-off-by: Jack Morgenstein <jackm@mellanox.co.il>
Signed-off-by: Vladimir Sokolovsky <vlad@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/mlx4/main.c b/drivers/net/mlx4/main.c
index a6aa49fc1d68..d3736013fe9b 100644
--- a/drivers/net/mlx4/main.c
+++ b/drivers/net/mlx4/main.c
@@ -485,6 +485,7 @@ static int mlx4_init_hca(struct mlx4_dev *dev)
         struct mlx4_priv          *priv = mlx4_priv(dev);
         struct mlx4_adapter        adapter;
         struct mlx4_dev_cap        dev_cap;
+        struct mlx4_mod_stat_cfg   mlx4_cfg;
         struct mlx4_profile        profile;
         struct mlx4_init_hca_param init_hca;
         u64 icm_size;
@@ -502,6 +503,12 @@ static int mlx4_init_hca(struct mlx4_dev *dev)
                 return err;
         }
 
+        mlx4_cfg.log_pg_sz_m = 1;
+        mlx4_cfg.log_pg_sz = 0;
+        err = mlx4_MOD_STAT_CFG(dev, &mlx4_cfg);
+        if (err)
+                mlx4_warn(dev, "Failed to override log_pg_sz parameter\n");
+
         err = mlx4_dev_cap(dev, &dev_cap);
         if (err) {
                 mlx4_err(dev, "QUERY_DEV_CAP command failed, aborting.\n");