mlx4_core: Workaround firmware bug in query dev cap

ConnectX firmware is supposed to report the number blue flame
registers per page as log2 of the value.  However, due to a firmware
bug, it reports actual number.  This patch works around this by
checking if the number of registers calculated fits within a page.  If
it does not, we use 8 registers per page.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/net/mlx4/fw.c

@@ -289,6 +289,10 @@ int mlx4_QUERY_DEV_CAP(struct mlx4_dev *dev, struct mlx4_dev_cap *dev_cap)
 		MLX4_GET(field, outbox, QUERY_DEV_CAP_LOG_BF_REG_SZ_OFFSET);
 		dev_cap->bf_reg_size = 1 << (field & 0x1f);
 		MLX4_GET(field, outbox, QUERY_DEV_CAP_LOG_MAX_BF_REGS_PER_PAGE_OFFSET);
+		if ((1 << (field & 0x3f)) > (PAGE_SIZE / dev_cap->bf_reg_size)) {
+			mlx4_warn(dev, "firmware bug: log2 # of blue flame regs is invalid (%d), forcing 3\n", field & 0x1f);
+			field = 3;
+		}
 		dev_cap->bf_regs_per_page = 1 << (field & 0x3f);
 		mlx4_dbg(dev, "BlueFlame available (reg size %d, regs/page %d)\n",
 			 dev_cap->bf_reg_size, dev_cap->bf_regs_per_page);