[PATCH net 1/2] net: dsa: sja1105: Force a negative value for enum sja1105_speed_t

[Vladimir Oltean]

The code in sja1105_adjust_port_config relies on the fact that an
invalid link speed is detected by sja1105_get_speed_cfg and returned as
-EINVAL.  However storing this into an enum that only has positive
members will cast it into an unsigned value, and it will miss the
negative check.

So make the -EINVAL value part of the enum, so that it is stored as a
signed number and passes the negative check.

Fixes: 8aa9ebccae87 ("net: dsa: Introduce driver for NXP SJA1105 5-port L2 
switch")
Signed-off-by: Vladimir Oltean <olte...@gmail.com>
---
 drivers/net/dsa/sja1105/sja1105.h      | 1 +
 drivers/net/dsa/sja1105/sja1105_main.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/sja1105/sja1105.h 
b/drivers/net/dsa/sja1105/sja1105.h
index 1e6d0f33a663..15df37ec63bf 100644
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -160,6 +160,7 @@ typedef enum {
        SJA1105_SPEED_100MBPS   = 2,
        SJA1105_SPEED_1000MBPS  = 1,
        SJA1105_SPEED_AUTO      = 0,
+       SJA1105_SPEED_INVALID   = -EINVAL,
 } sja1105_speed_t;
 
 int sja1105pqrs_setup_rgmii_delay(const void *ctx, int port);
diff --git a/drivers/net/dsa/sja1105/sja1105_main.c 
b/drivers/net/dsa/sja1105/sja1105_main.c
index b89d979ba213..12b1af52d84b 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -719,7 +719,7 @@ static sja1105_speed_t sja1105_get_speed_cfg(unsigned int 
speed_mbps)
        for (i = SJA1105_SPEED_AUTO; i <= SJA1105_SPEED_1000MBPS; i++)
                if (sja1105_speed[i] == speed_mbps)
                        return i;
-       return -EINVAL;
+       return SJA1105_SPEED_INVALID;
 }
 
 /* Set link speed and enable/disable traffic I/O in the MAC configuration
-- 
2.17.1