Re: [PATCH v7 3/4] drm/loongson: Add interrupt driver for LS7A.

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

Hi Chenyang,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on linus/master v5.19-rc6 next-20220708]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Chenyang-Li/drm-loongson-Add-DRM-Driver-for-Loongson-7A1000-bridge-chip/20220625-171037
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20220712/202207120454.PJBS1e9p-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 77a38f6839980bfac61babb40d83772c51427011)
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
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/7cad653ee3a3b83188e2d91335269753e134b808
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Chenyang-Li/drm-loongson-Add-DRM-Driver-for-Loongson-7A1000-bridge-chip/20220625-171037
        git checkout 7cad653ee3a3b83188e2d91335269753e134b808
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/gpu/drm/loongson/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/loongson/loongson_irq.c:24:11: warning: variable 'lcrtc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           else if (val & FB_VSYNC1_INT)
                    ^~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/loongson/loongson_irq.c:27:26: note: uninitialized use occurs here
           drm_crtc_handle_vblank(&lcrtc->base);
                                   ^~~~~
   drivers/gpu/drm/loongson/loongson_irq.c:24:7: note: remove the 'if' if its condition is always true
           else if (val & FB_VSYNC1_INT)
                ^~~~~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/loongson/loongson_irq.c:16:29: note: initialize the variable 'lcrtc' to silence this warning
           struct loongson_crtc *lcrtc;
                                      ^
                                       = NULL
   1 warning generated.


vim +24 drivers/gpu/drm/loongson/loongson_irq.c

    11	
    12	static irqreturn_t loongson_irq_handler(int irq, void *arg)
    13	{
    14		struct drm_device *dev = (struct drm_device *) arg;
    15		struct loongson_device *ldev = to_loongson_device(dev);
    16		struct loongson_crtc *lcrtc;
    17		u32 val;
    18	
    19		val = ls7a_mm_rreg(ldev, FB_INT_REG);
    20		ls7a_mm_wreg(ldev, FB_INT_REG, val & (0xffff << 16));
    21	
    22		if (val & FB_VSYNC0_INT)
    23			lcrtc = ldev->mode_info[0].crtc;
  > 24		else if (val & FB_VSYNC1_INT)
    25			lcrtc = ldev->mode_info[1].crtc;
    26	
    27		drm_crtc_handle_vblank(&lcrtc->base);
    28	
    29		return IRQ_HANDLED;
    30	}
    31	

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