From: Lo-an Chen <lo-an.chen@amd.com>
Date: Thu, 14 Nov 2024 09:53:41 +0000 (+0800)
Subject: drm/amd/display: Correct prefetch calculation
X-Git-Tag: v6.13-rc2~14^2^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=24d3749c11d949972d8c22e75567dc90ff5482e7;p=thirdparty%2Fkernel%2Flinux.git

drm/amd/display: Correct prefetch calculation

[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@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Lo-an Chen <lo-an.chen@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---

diff --git a/drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c b/drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c
index d851c081e3768..8dabb1ac0b684 100644
--- 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 CalculatePrefetchSchedule(struct display_mode_lib_scratch_st *
 	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);