Re: [PATCH] ACPI: LPSS: Use ACPI_COMPANION() directly

Hi "Rafael,

I love your patch! Perhaps something to improve:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on v5.15-rc4 next-20211008]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Rafael-J-Wysocki/ACPI-LPSS-Use-ACPI_COMPANION-directly/20211009-222505
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: i386-randconfig-a013-20211009 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 30caca39f401ae17927439c0a0bd6d1b1916dd6a)
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/0day-ci/linux/commit/6fd0aa7da4af33b790cf8e5a943fe2795a8f215a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Rafael-J-Wysocki/ACPI-LPSS-Use-ACPI_COMPANION-directly/20211009-222505
        git checkout 6fd0aa7da4af33b790cf8e5a943fe2795a8f215a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=i386 

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

All warnings (new ones prefixed by >>):

quoted

drivers/acpi/acpi_lpss.c:729:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]

           if (WARN_ON(!pdata || !pdata->mmio_base)) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/asm-generic/bug.h:120:28: note: expanded from macro 'WARN_ON'
   #define WARN_ON(condition) ({                                           \
                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/acpi/acpi_lpss.c:737:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   drivers/acpi/acpi_lpss.c:729:2: note: remove the 'if' if its condition is always true
           if (WARN_ON(!pdata || !pdata->mmio_base)) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/acpi/acpi_lpss.c:718:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   1 warning generated.


vim +729 drivers/acpi/acpi_lpss.c

1a8f83515c1646 Rafael J. Wysocki 2014-02-11  712  
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  713  static int lpss_reg_read(struct device *dev, unsigned int reg, u32 *val)
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  714  {
6fd0aa7da4af33 Rafael J. Wysocki 2021-10-09  715  	struct acpi_device *adev = ACPI_COMPANION(dev);
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  716  	struct lpss_private_data *pdata;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  717  	unsigned long flags;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  718  	int ret;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  719  
6fd0aa7da4af33 Rafael J. Wysocki 2021-10-09  720  	if (WARN_ON(!adev))
6fd0aa7da4af33 Rafael J. Wysocki 2021-10-09  721  		return -ENODEV;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  722  
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  723  	spin_lock_irqsave(&dev->power.lock, flags);
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  724  	if (pm_runtime_suspended(dev)) {
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  725  		ret = -EAGAIN;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  726  		goto out;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  727  	}
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  728  	pdata = acpi_driver_data(adev);
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06 @729  	if (WARN_ON(!pdata || !pdata->mmio_base)) {
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  730  		ret = -ENODEV;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  731  		goto out;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  732  	}
1a8f83515c1646 Rafael J. Wysocki 2014-02-11  733  	*val = __lpss_reg_read(pdata, reg);
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  734  
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  735   out:
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  736  	spin_unlock_irqrestore(&dev->power.lock, flags);
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  737  	return ret;
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  738  }
2e0f8822d1a6d8 Rafael J. Wysocki 2013-03-06  739  

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