Hello Ethan Bitnun,
Commit bd051aa2fcfb ("drm/amd/display: Find max flickerless instant
vtotal delta") from Apr 1, 2024 (linux-next), leads to the following
Smatch static checker warning:
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)'
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c
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;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
stream->timing.v_total is u32 so it makes the subtract u32 thus it's
always >= 0.
1007
1008 return ((safe_refresh_v_total - stream->timing.v_total) >= 0) ? (safe_refresh_v_total - stream->timing.v_total) : 0;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Same.
1009 }
regards,
dan carpenter
