[PATCH net 2/2] net: mscc: ocelot: warn when encoding an out-of-bounds watermark value

[Vladimir Oltean]

There is an upper bound to the value that a watermark may hold. That
upper bound is not immediately obvious during configuration, and it
might be possible to have accidental truncation.

Actually this has happened already, add a warning to prevent it from
happening again.

Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
---
 drivers/net/dsa/ocelot/felix_vsc9959.c     | 2 ++
 drivers/net/dsa/ocelot/seville_vsc9953.c   | 2 ++
 drivers/net/ethernet/mscc/ocelot_vsc7514.c | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c 
b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 4fc67ff212de..cb0f3d28ecac 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -998,6 +998,8 @@ static int vsc9959_prevalidate_phy_mode(struct ocelot 
*ocelot, int port,
  */
 static u16 vsc9959_wm_enc(u16 value)
 {
+       WARN_ON(value >= 16 * BIT(8));
+
        if (value >= BIT(8))
                return BIT(8) | (value / 16);
 
diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c 
b/drivers/net/dsa/ocelot/seville_vsc9953.c
index e993f3eac3eb..76576cf0ba8a 100644
--- a/drivers/net/dsa/ocelot/seville_vsc9953.c
+++ b/drivers/net/dsa/ocelot/seville_vsc9953.c
@@ -1049,6 +1049,8 @@ static int vsc9953_prevalidate_phy_mode(struct ocelot 
*ocelot, int port,
  */
 static u16 vsc9953_wm_enc(u16 value)
 {
+       WARN_ON(value >= 16 * BIT(9));
+
        if (value >= BIT(9))
                return BIT(9) | (value / 16);
 
diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c 
b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
index f3e54589e6d6..79b88bc69c75 100644
--- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
+++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
@@ -754,6 +754,8 @@ static int ocelot_reset(struct ocelot *ocelot)
  */
 static u16 ocelot_wm_enc(u16 value)
 {
+       WARN_ON(value >= 16 * BIT(8));
+
        if (value >= BIT(8))
                return BIT(8) | (value / 16);
 
-- 
2.25.1