[frank-w-bpi-r2-4.14:6.16-dualmmc 59/79] drivers/net/pcs/pcs-airoha.c:2537:2: warning: unannotated fall-through between switch labels

[frank-w-bpi-r2-4.14:6.16-dualmmc 59/79] drivers/net/pcs/pcs-airoha.c:2537:2: warning: unannotated fall-through between switch labels

[kernel test robot]

tree:   https://github.com/frank-w/BPI-R2-4.14 6.16-dualmmc
head:   61605f260a207bbe9994a325ea9b2d33e29d62de
commit: 65cc15faa14410dfb08f3a921b4ac794ec08f597 [59/79] net: pcs: airoha: add PCS driver for Airoha SoC
config: x86_64-buildonly-randconfig-2001-20250721 (https://download.01.org/0day-ci/archive/20250721/202507210301.B6NM09ms-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250721/202507210301.B6NM09ms-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507210301.B6NM09ms-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/pcs/pcs-airoha.c:2537:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
    2537 |         default:
         |         ^
   drivers/net/pcs/pcs-airoha.c:2537:2: note: insert '__attribute__((fallthrough));' to silence this warning
    2537 |         default:
         |         ^
         |         __attribute__((fallthrough)); 
   drivers/net/pcs/pcs-airoha.c:2537:2: note: insert 'break;' to avoid fall-through
    2537 |         default:
         |         ^
         |         break; 
   1 warning generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for FWNODE_PCS
   Depends on [n]: NETDEVICES [=y] && (ACPI [=n] || OF [=n]) && PHYLINK [=m]
   Selected by [y]:
   - PCS_AIROHA [=y] && NETDEVICES [=y]


vim +2537 drivers/net/pcs/pcs-airoha.c

  2516	
  2517	static void airoha_pcs_an_restart(struct phylink_pcs *pcs)
  2518	{
  2519		struct airoha_pcs_priv *priv = phylink_pcs_to_airoha_pcs_port(pcs);
  2520	
  2521		switch (priv->interface) {
  2522		case PHY_INTERFACE_MODE_SGMII:
  2523		case PHY_INTERFACE_MODE_1000BASEX:
  2524		case PHY_INTERFACE_MODE_2500BASEX:
  2525			regmap_set_bits(priv->hsgmii_an, AIROHA_PCS_HSGMII_AN_SGMII_REG_AN_0,
  2526					AIROHA_PCS_HSGMII_AN_SGMII_AN_RESTART);
  2527			udelay(3);
  2528			regmap_clear_bits(priv->hsgmii_an, AIROHA_PCS_HSGMII_AN_SGMII_REG_AN_0,
  2529					  AIROHA_PCS_HSGMII_AN_SGMII_AN_RESTART);
  2530			break;
  2531		case PHY_INTERFACE_MODE_USXGMII:
  2532			regmap_set_bits(priv->usxgmii_pcs, AIROHA_PCS_USXGMII_PCS_AN_CONTROL_0,
  2533					AIROHA_PCS_USXGMII_AN_RESTART);
  2534			udelay(3);
  2535			regmap_clear_bits(priv->usxgmii_pcs, AIROHA_PCS_USXGMII_PCS_AN_CONTROL_0,
  2536					  AIROHA_PCS_USXGMII_AN_RESTART);
> 2537		default:
  2538			return;
  2539		}
  2540	}
  2541	

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https://github.com/intel/lkp-tests/wiki