[linux-next:master 7648/9984] drivers/gpu/drm/i915/display/intel_dsb.c:363 _intel_dsb_commit() warn: always true condition '(dewake_scanline >= 0) => (0-u32max >= 0)'

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   7d730f1bf6f39ece2d9f3ae682f12e5b593d534d
commit: f83b94d23770c234cdc51a1468b3ce9d7e42f20e [7648/9984] drm/i915/dsb: Use DEwake to combat PkgC latency
config: x86_64-randconfig-161-20231005 (https://download.01.org/0day-ci/archive/20231005/202310052201.AnVbpgPr-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce: (https://download.01.org/0day-ci/archive/20231005/202310052201.AnVbpgPr-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/202310052201.AnVbpgPr-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/i915/display/intel_dsb.c:363 _intel_dsb_commit() warn: always true condition '(dewake_scanline >= 0) => (0-u32max >= 0)'

vim +363 drivers/gpu/drm/i915/display/intel_dsb.c

   338	
   339	static void _intel_dsb_commit(struct intel_dsb *dsb, u32 ctrl,
   340				      unsigned int dewake_scanline)
   341	{
   342		struct intel_crtc *crtc = dsb->crtc;
   343		struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
   344		enum pipe pipe = crtc->pipe;
   345		u32 tail;
   346	
   347		tail = dsb->free_pos * 4;
   348		if (drm_WARN_ON(&dev_priv->drm, !IS_ALIGNED(tail, CACHELINE_BYTES)))
   349			return;
   350	
   351		if (is_dsb_busy(dev_priv, pipe, dsb->id)) {
   352			drm_err(&dev_priv->drm, "[CRTC:%d:%s] DSB %d is busy\n",
   353				crtc->base.base.id, crtc->base.name, dsb->id);
   354			return;
   355		}
   356	
   357		intel_de_write_fw(dev_priv, DSB_CTRL(pipe, dsb->id),
   358				  ctrl | DSB_ENABLE);
   359	
   360		intel_de_write_fw(dev_priv, DSB_HEAD(pipe, dsb->id),
   361				  i915_ggtt_offset(dsb->vma));
   362	
 > 363		if (dewake_scanline >= 0) {
   364			int diff, hw_dewake_scanline;
   365	
   366			hw_dewake_scanline = intel_crtc_scanline_to_hw(crtc, dewake_scanline);
   367	
   368			intel_de_write_fw(dev_priv, DSB_PMCTRL(pipe, dsb->id),
   369					  DSB_ENABLE_DEWAKE |
   370					  DSB_SCANLINE_FOR_DEWAKE(hw_dewake_scanline));
   371	
   372			/*
   373			 * Force DEwake immediately if we're already past
   374			 * or close to racing past the target scanline.
   375			 */
   376			diff = dewake_scanline - intel_get_crtc_scanline(crtc);
   377			intel_de_write_fw(dev_priv, DSB_PMCTRL_2(pipe, dsb->id),
   378					  (diff >= 0 && diff < 5 ? DSB_FORCE_DEWAKE : 0) |
   379					  DSB_BLOCK_DEWAKE_EXTENSION);
   380		}
   381	
   382		intel_de_write_fw(dev_priv, DSB_TAIL(pipe, dsb->id),
   383				  i915_ggtt_offset(dsb->vma) + tail);
   384	}
   385	

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