[xlnx:master 39/98] drivers/net/ethernet/xilinx/xilinx_axienet_main.c:1962:10: warning: 'regval' may be used uninitialized in this function

tree:   https://github.com/Xilinx/linux-xlnx master
head:   664f8a639f658d0964f7cbd030aa95f42d6c4567
commit: b83c55d11cbd986418edbf4b407ab0c8bbe2efb8 [39/98] net: xilinx: XXV Ethernet HW timestamp fixes
config: riscv-allyesconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/Xilinx/linux-xlnx/commit/b83c55d11cbd986418edbf4b407ab0c8bbe2efb8
        git remote add xlnx https://github.com/Xilinx/linux-xlnx
        git fetch --no-tags xlnx master
        git checkout b83c55d11cbd986418edbf4b407ab0c8bbe2efb8
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/xilinx/xilinx_axienet_main.c: In function 'axienet_queue_xmit':
   drivers/net/ethernet/xilinx/xilinx_axienet_main.c:1077:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
    1077 |   const struct ethhdr *eth;
         |   ^~~~~
   drivers/net/ethernet/xilinx/xilinx_axienet_main.c: In function 'axienet_ioctl':

quoted

drivers/net/ethernet/xilinx/xilinx_axienet_main.c:1962:10: warning: 'regval' may be used uninitialized in this function [-Wmaybe-uninitialized]

    1962 |   regval &= ~XAE_TC_INBAND1588_MASK;
   drivers/net/ethernet/xilinx/xilinx_axienet_main.c:1927:6: note: 'regval' was declared here
    1927 |  u32 regval;
         |      ^~~~~~

vim +/regval +1962 drivers/net/ethernet/xilinx/xilinx_axienet_main.c

bff352467d6de71 Saurabh Sengar               2020-02-13  1951  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1952  	/* reserved for future extensions */
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1953  	if (config->flags)
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1954  		return -EINVAL;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1955  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1956  	/* Read the current value in the MAC TX CTRL register */
b83c55d11cbd986 Harini Katakam               2020-09-24  1957  	if (lp->axienet_config->mactype != XAXIENET_10G_25G)
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1958  		regval = axienet_ior(lp, XAE_TC_OFFSET);
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1959  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1960  	switch (config->tx_type) {
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1961  	case HWTSTAMP_TX_OFF:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24 @1962  		regval &= ~XAE_TC_INBAND1588_MASK;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1963  		break;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1964  	case HWTSTAMP_TX_ON:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1965  		config->tx_type = HWTSTAMP_TX_ON;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1966  		regval |= XAE_TC_INBAND1588_MASK;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1967  		break;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1968  	case HWTSTAMP_TX_ONESTEP_SYNC:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1969  		config->tx_type = HWTSTAMP_TX_ONESTEP_SYNC;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1970  		regval |= XAE_TC_INBAND1588_MASK;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1971  		break;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1972  	default:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1973  		return -ERANGE;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1974  	}
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1975  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1976  	if (lp->axienet_config->mactype != XAXIENET_10G_25G)
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1977  		axienet_iow(lp, XAE_TC_OFFSET, regval);
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1978  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1979  	/* Read the current value in the MAC RX RCW1 register */
b83c55d11cbd986 Harini Katakam               2020-09-24  1980  	if (lp->axienet_config->mactype != XAXIENET_10G_25G)
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1981  		regval = axienet_ior(lp, XAE_RCW1_OFFSET);
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1982  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1983  	/* On RX always timestamp everything */
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1984  	switch (config->rx_filter) {
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1985  	case HWTSTAMP_FILTER_NONE:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1986  		regval &= ~XAE_RCW1_INBAND1588_MASK;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1987  		break;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1988  	default:
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1989  		config->rx_filter = HWTSTAMP_FILTER_ALL;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1990  		regval |= XAE_RCW1_INBAND1588_MASK;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1991  	}
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1992  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1993  	if (lp->axienet_config->mactype != XAXIENET_10G_25G)
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1994  		axienet_iow(lp, XAE_RCW1_OFFSET, regval);
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1995  
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1996  	return 0;
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1997  }
6a8544f2f4d9002 Appana Durga Kedareswara Rao 2020-01-24  1998  

:::::: The code at line 1962 was first introduced by commit
:::::: 6a8544f2f4d90023366c63699944ce4f7d0d5b5d net: axienet: Add support for 1588

:::::: TO: Appana Durga Kedareswara Rao [off-list ref]
:::::: CC: Michal Simek [off-list ref]

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org