Re: [PATCH net-next v3 4/4] net: ftgmac100: Add RGMII delay support for AST2600

[kernel test robot <lkp@intel.com>]

Hi Jacky,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 01cc760632b875c4ad0d8fec0b0c01896b8a36d4]

url:    https://github.com/intel-lab-lkp/linux/commits/Jacky-Chou/dt-bindings-net-ftgmac100-Add-delay-properties-for-AST2600/20251103-154258
base:   01cc760632b875c4ad0d8fec0b0c01896b8a36d4
patch link:    https://lore.kernel.org/r/20251103-rgmii_delay_2600-v3-4-e2af2656f7d7%40aspeedtech.com
patch subject: [PATCH net-next v3 4/4] net: ftgmac100: Add RGMII delay support for AST2600
config: arm-defconfig (https://download.01.org/0day-ci/archive/20251104/202511041023.QGAHaAZ3-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project d2625a438020ad35330cda29c3def102c1687b1b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251104/202511041023.QGAHaAZ3-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/202511041023.QGAHaAZ3-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/ethernet/faraday/ftgmac100.c:1865:13: warning: variable 'rgmii_delay_unit' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
    1865 |         } else if (of_device_is_compatible(np, "aspeed,ast2600-mac23")) {
         |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/faraday/ftgmac100.c:1870:53: note: uninitialized use occurs here
    1870 |         rgmii_tx_delay = DIV_ROUND_CLOSEST(rgmii_tx_delay, rgmii_delay_unit);
         |                                                            ^~~~~~~~~~~~~~~~
   drivers/net/ethernet/faraday/ftgmac100.c:1865:9: note: remove the 'if' if its condition is always true
    1865 |         } else if (of_device_is_compatible(np, "aspeed,ast2600-mac23")) {
         |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/faraday/ftgmac100.c:1844:22: note: initialize the variable 'rgmii_delay_unit' to silence this warning
    1844 |         u32 rgmii_delay_unit;
         |                             ^
         |                              = 0
   1 warning generated.


vim +1865 drivers/net/ethernet/faraday/ftgmac100.c

  1838	
  1839	static int ftgmac100_set_ast2600_rgmii_delay(struct platform_device *pdev,
  1840						     u32 rgmii_tx_delay,
  1841						     u32 rgmii_rx_delay)
  1842	{
  1843		struct device_node *np = pdev->dev.of_node;
  1844		u32 rgmii_delay_unit;
  1845		struct regmap *scu;
  1846		int dly_mask;
  1847		int dly_reg;
  1848		int id;
  1849	
  1850		scu = syscon_regmap_lookup_by_phandle(np, "scu");
  1851		if (IS_ERR(scu)) {
  1852			dev_err(&pdev->dev, "failed to get scu");
  1853			return PTR_ERR(scu);
  1854		}
  1855	
  1856		id = of_alias_get_id(np, "ethernet");
  1857		if (id < 0 || id > 3) {
  1858			dev_err(&pdev->dev, "get wrong alise id %d\n", id);
  1859			return -EINVAL;
  1860		}
  1861	
  1862		if (of_device_is_compatible(np, "aspeed,ast2600-mac01")) {
  1863			dly_reg = AST2600_MAC01_CLK_DLY;
  1864			rgmii_delay_unit = AST2600_MAC01_CLK_DLY_UNIT;
> 1865		} else if (of_device_is_compatible(np, "aspeed,ast2600-mac23")) {
  1866			dly_reg = AST2600_MAC23_CLK_DLY;
  1867			rgmii_delay_unit = AST2600_MAC23_CLK_DLY_UNIT;
  1868		}
  1869	
  1870		rgmii_tx_delay = DIV_ROUND_CLOSEST(rgmii_tx_delay, rgmii_delay_unit);
  1871		if (rgmii_tx_delay >= 32) {
  1872			dev_err(&pdev->dev,
  1873				"The index %u of TX delay setting is out of range\n",
  1874				rgmii_tx_delay);
  1875			return -EINVAL;
  1876		}
  1877	
  1878		rgmii_rx_delay = DIV_ROUND_CLOSEST(rgmii_rx_delay, rgmii_delay_unit);
  1879		if (rgmii_rx_delay >= 32) {
  1880			dev_err(&pdev->dev,
  1881				"The index %u of RX delay setting is out of range\n",
  1882				rgmii_rx_delay);
  1883			return -EINVAL;
  1884		}
  1885	
  1886		/* Due to the hardware design reason, for MAC23 on AST2600, the zero
  1887		 * delay ns on RX is configured by setting value 0x1a.
  1888		 * List as below:
  1889		 * 0x1a -> 0   ns, 0x1b -> 0.25 ns, ... , 0x1f -> 1.25 ns,
  1890		 * 0x00 -> 1.5 ns, 0x01 -> 1.75 ns, ... , 0x19 -> 7.75 ns, 0x1a -> 0 ns
  1891		 */
  1892		if (of_device_is_compatible(np, "aspeed,ast2600-mac23"))
  1893			rgmii_rx_delay = (AST2600_MAC23_RX_DLY_0_NS + rgmii_rx_delay) &
  1894					 AST2600_MAC_TX_RX_DLY_MASK;
  1895	
  1896		if (id == 0 || id == 2) {
  1897			dly_mask = ASPEED_MAC0_2_TX_DLY | ASPEED_MAC0_2_RX_DLY;
  1898			rgmii_tx_delay = FIELD_PREP(ASPEED_MAC0_2_TX_DLY, rgmii_tx_delay);
  1899			rgmii_rx_delay = FIELD_PREP(ASPEED_MAC0_2_RX_DLY, rgmii_rx_delay);
  1900		} else {
  1901			dly_mask = ASPEED_MAC1_3_TX_DLY | ASPEED_MAC1_3_RX_DLY;
  1902			rgmii_tx_delay = FIELD_PREP(ASPEED_MAC1_3_TX_DLY, rgmii_tx_delay);
  1903			rgmii_rx_delay = FIELD_PREP(ASPEED_MAC1_3_RX_DLY, rgmii_rx_delay);
  1904		}
  1905	
  1906		regmap_update_bits(scu, dly_reg, dly_mask, rgmii_tx_delay | rgmii_rx_delay);
  1907	
  1908		return 0;
  1909	}
  1910	

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