[bug report] net: dsa: mt7530: Add the support of MT7531 switch

[Landen Chao]

Hello Dan,

Thanks for your review.
On Wed, 2020-09-16 at 22:35 +0800, Dan Carpenter wrote:
> Hello Landen Chao,
> 
> The patch c288575f7810: "net: dsa: mt7530: Add the support of MT7531
> switch" from Sep 11, 2020, leads to the following static checker
> warning:
> 
> 	drivers/net/dsa/mt7530.c:2298 mt7531_cpu_port_config()
> 	error: uninitialized symbol 'interface'.
> 
> drivers/net/dsa/mt7530.c
>   2273  static int
>   2274  mt7531_cpu_port_config(struct dsa_switch *ds, int port)
>   2275  {
>   2276          struct mt7530_priv *priv = ds->priv;
>   2277          phy_interface_t interface;
>   2278          int speed;
>   2279  
>   2280          switch (port) {
>   2281          case 5:
>   2282                  if (mt7531_is_rgmii_port(priv, port))
>   2283                          interface = PHY_INTERFACE_MODE_RGMII;
>   2284                  else
>   2285                          interface = PHY_INTERFACE_MODE_2500BASEX;
>   2286  
>   2287                  priv->p5_interface = interface;
>   2288                  break;
>   2289          case 6:
>   2290                  interface = PHY_INTERFACE_MODE_2500BASEX;
>   2291  
>   2292                  mt7531_pad_setup(ds, interface);
>   2293  
>   2294                  priv->p6_interface = interface;
>   2295                  break;
> 
> Does this need a default case?  Smatch thinks "port" can be 0-6.
Yes, it needs a default case to catch unexpected dts setting. "port" can
be 0-6 generally, but only 5 and 6 are valid cpu port.

Although, "port" 0-4 can also be labeled as "cpu" in dts, but no real
hardware can support this kind of configuration currently.
> 
>   2296          }
>   2297  
>   2298          if (interface == PHY_INTERFACE_MODE_2500BASEX)
>   2299                  speed = SPEED_2500;
>   2300          else
>   2301                  speed = SPEED_1000;
>   2302  
>   2303          mt7531_mac_config(ds, port, MLO_AN_FIXED, interface);
>   2304          mt7530_write(priv, MT7530_PMCR_P(port),
>   2305                       PMCR_CPU_PORT_SETTING(priv->id));
>   2306          mt753x_phylink_mac_link_up(ds, port, MLO_AN_FIXED, interface, NULL,
>   2307                                     speed, DUPLEX_FULL, true, true);
>   2308  
>   2309          return 0;
>   2310  }
> 
> regards,
> dan carpenter
regards,
landen