6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lo-an Chen <lo-an.chen@xxxxxxx>
commit 24d3749c11d949972d8c22e75567dc90ff5482e7 upstream.
[WHY]
The minimum value of the dst_y_prefetch_equ was not correct
in prefetch calculation whice causes OPTC underflow.
[HOW]
Add the min operation of dst_y_prefetch_equ in prefetch calculation.
Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Signed-off-by: Lo-an Chen <lo-an.chen@xxxxxxx>
Signed-off-by: Alex Hung <alex.hung@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c
@@ -1222,6 +1222,7 @@ static dml_bool_t CalculatePrefetchSched
s->dst_y_prefetch_oto = s->Tvm_oto_lines + 2 * s->Tr0_oto_lines + s->Lsw_oto;
s->dst_y_prefetch_equ = p->VStartup - (*p->TSetup + dml_max(p->TWait + p->TCalc, *p->Tdmdl)) / s->LineTime - (*p->DSTYAfterScaler + (dml_float_t) *p->DSTXAfterScaler / (dml_float_t)p->myPipe->HTotal);
+ s->dst_y_prefetch_equ = dml_min(s->dst_y_prefetch_equ, 63.75); // limit to the reg limit of U6.2 for DST_Y_PREFETCH
#ifdef __DML_VBA_DEBUG__
dml_print("DML::%s: HTotal = %u\n", __func__, p->myPipe->HTotal);
