NTB: Enable Snoop on Primary Side

Enable Snoop from Primary to Secondary side on BAR23 and BAR45 on all
TLPs.  Previously, Snoop was only enabled from Secondary to Primary
side.  This can have a performance improvement on some workloads.

Also, make the code more obvious about how the link is being enabled.

Signed-off-by: Jon Mason <jon.mason@intel.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
index 391c377a5d38..80505aeecf9e 100644
--- a/drivers/ntb/ntb_hw.c
+++ b/drivers/ntb/ntb_hw.c
@@ -1316,10 +1316,16 @@ static void ntb_hw_link_up(struct ntb_device *ndev)
 {
         if (ndev->conn_type == NTB_CONN_TRANSPARENT)
                 ntb_link_event(ndev, NTB_LINK_UP);
-        else
+        else {
+                u32 ntb_cntl;
+
                 /* Let's bring the NTB link up */
-                writel(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP,
-                       ndev->reg_ofs.lnk_cntl);
+                ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
+                ntb_cntl &= ~(NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK);
+                ntb_cntl |= NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP;
+                ntb_cntl |= NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP;
+                writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
+        }
 }
 
 static void ntb_hw_link_down(struct ntb_device *ndev)
@@ -1333,8 +1339,9 @@ static void ntb_hw_link_down(struct ntb_device *ndev)
 
         /* Bring NTB link down */
         ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
-        ntb_cntl &= ~(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP);
-        ntb_cntl |= NTB_CNTL_LINK_DISABLE;
+        ntb_cntl &= ~(NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP);
+        ntb_cntl &= ~(NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP);
+        ntb_cntl |= NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK;
         writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
 }