[linux-next:master 12471/13491] drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:1006 dc_stream_get_max_flickerless_instant_vtotal_delta() warn: always true condition '((stream->timing.v_total - safe_refresh_v_total) >= 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:   632483ea8004edfadd035de36e1ab2c7c4f53158
commit: bd051aa2fcfb803b94708429970f71596a4748e4 [12471/13491] drm/amd/display: Find max flickerless instant vtotal delta
config: x86_64-randconfig-161-20240520 (https://download.01.org/0day-ci/archive/20240520/202405202243.SHvS2otq-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0

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/202405202243.SHvS2otq-lkp@intel.com/

New smatch warnings:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:1006 dc_stream_get_max_flickerless_instant_vtotal_delta() warn: always true condition '((stream->timing.v_total - safe_refresh_v_total) >= 0) => (0-u32max >= 0)'
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:1008 dc_stream_get_max_flickerless_instant_vtotal_delta() warn: always true condition '((safe_refresh_v_total - stream->timing.v_total) >= 0) => (0-u32max >= 0)'

Old smatch warnings:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:398 dc_stream_program_cursor_position() error: we previously assumed 'stream' could be null (see line 397)

vim +1006 drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c

   985	
   986	/*
   987	 * Determines the max flickerless instant vtotal delta for a stream.
   988	 * Determines vtotal increase/decrease based on the bool "increase"
   989	 */
   990	static unsigned int dc_stream_get_max_flickerless_instant_vtotal_delta(struct dc_stream_state *stream, bool is_gaming, bool increase)
   991	{
   992		if (stream->timing.v_total * stream->timing.h_total == 0)
   993			return 0;
   994	
   995		int current_refresh_hz = (int)div64_s64((long long)stream->timing.pix_clk_100hz*100, stream->timing.v_total*stream->timing.h_total);
   996	
   997		int safe_refresh_hz = dc_stream_calculate_flickerless_refresh_rate(stream,
   998								 dc_stream_get_brightness_millinits_from_refresh(stream, current_refresh_hz),
   999								 current_refresh_hz,
  1000								 is_gaming,
  1001								 increase);
  1002	
  1003		int safe_refresh_v_total = (int)div64_s64((long long)stream->timing.pix_clk_100hz*100, safe_refresh_hz*stream->timing.h_total);
  1004	
  1005		if (increase)
> 1006			return ((stream->timing.v_total - safe_refresh_v_total) >= 0) ? (stream->timing.v_total - safe_refresh_v_total) : 0;
  1007	
> 1008		return ((safe_refresh_v_total - stream->timing.v_total) >= 0) ? (safe_refresh_v_total - stream->timing.v_total) : 0;
  1009	}
  1010	

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