drm/amd/display: Fix UBSAN: shift-out-of-bounds warning

[Why]
On NAVI14 CONFIG_UBSAN reported shift-out-of-bounds at
display_rq_dlg_calc_20v2.c:304:38

rq_param->misc.rq_c.blk256_height is 0 when chroma(*_c) is invalid.
dml_log2 returns -1023 for log2(0), although log2(0) is undefined.

Which ended up as:
rq_param->dlg.rq_c.swath_height = 1 << -1023

[How]
Fix applied on all dml versions.
1. Ensure dml_log2 is only called if the argument is greater than 0.
2. Subtract req128_l/req128_c from log2_swath_height_l/log2_swath_height_c
   only when it is greater than 0.

Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Anson Jacob <[email protected]>
Reviewed-by: Dmytro Laktyushkin <[email protected]>
Reviewed-by: Jun Lei <[email protected]>
Acked-by: Solomon Chiu <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

0 files changed, 0 insertions, 0 deletions