drm/amd/display: Guard DST_Y_PREFETCH register overflow in DCN21

[why]
DST_Y_PREFETCH can overflow when DestinationLinesForPrefetch values are
too large due to the former being limited to 8 bits.

[how]
Set the maximum value of DestinationLinesForPrefetch to be 255 * refclk
period.

Reviewed-by: Laktyushkin Dmytro <dmytro.laktyushkin@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Victor Lu <victorchengchi.lu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Victor Lu 2021-07-08 14:50:48 -04:00 committed by Alex Deucher
parent 91e273712a
commit c8f8e96805

View File

@ -841,6 +841,9 @@ static bool CalculatePrefetchSchedule(
else
*DestinationLinesForPrefetch = dst_y_prefetch_equ;
// Limit to prevent overflow in DST_Y_PREFETCH register
*DestinationLinesForPrefetch = dml_min(*DestinationLinesForPrefetch, 63.75);
dml_print("DML: VStartup: %d\n", VStartup);
dml_print("DML: TCalc: %f\n", TCalc);
dml_print("DML: TWait: %f\n", TWait);