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drm/amd/display: Require minimum VBlank size for stutter optimization

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If the nominal VBlank is too small, optimizing for stutter can cause
the prefetch bandwidth to increase drasticaly, resulting in higher
clock and power requirements. Only optimize if it is >3x the stutter
latency.

Reviewed-by: Austin Zheng <austin.zheng@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 003215f962)
Cc: stable@vger.kernel.org
This commit is contained in:
Dillon Varone
2024-11-01 12:00:14 -04:00
committed by Alex Deucher
parent 6825cb07b7
commit 9fc0cbcb6e
1 changed files with 9 additions and 2 deletions
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11
drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c
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@@ -8,6 +8,7 @@
#include "dml2_pmo_dcn4_fams2.h"
static const double MIN_VACTIVE_MARGIN_PCT = 0.25; // We need more than non-zero margin because DET buffer granularity can alter vactive latency hiding
static const double MIN_BLANK_STUTTER_FACTOR = 3.0;
static const struct dml2_pmo_pstate_strategy base_strategy_list_1_display[] = {
// VActive Preferred
@@ -2139,6 +2140,7 @@ bool pmo_dcn4_fams2_init_for_stutter(struct dml2_pmo_init_for_stutter_in_out *in
struct dml2_pmo_instance *pmo = in_out->instance;
bool stutter_period_meets_z8_eco = true;
bool z8_stutter_optimization_too_expensive = false;
bool stutter_optimization_too_expensive = false;
double line_time_us, vblank_nom_time_us;
unsigned int i;
@@ -2160,10 +2162,15 @@ bool pmo_dcn4_fams2_init_for_stutter(struct dml2_pmo_init_for_stutter_in_out *in
line_time_us = (double)in_out->base_display_config->display_config.stream_descriptors[i].timing.h_total / (in_out->base_display_config->display_config.stream_descriptors[i].timing.pixel_clock_khz * 1000) * 1000000;
vblank_nom_time_us = line_time_us * in_out->base_display_config->display_config.stream_descriptors[i].timing.vblank_nom;
if (vblank_nom_time_us < pmo->soc_bb->power_management_parameters.z8_stutter_exit_latency_us) {
if (vblank_nom_time_us < pmo->soc_bb->power_management_parameters.z8_stutter_exit_latency_us * MIN_BLANK_STUTTER_FACTOR) {
z8_stutter_optimization_too_expensive = true;
break;
}
if (vblank_nom_time_us < pmo->soc_bb->power_management_parameters.stutter_enter_plus_exit_latency_us * MIN_BLANK_STUTTER_FACTOR) {
stutter_optimization_too_expensive = true;
break;
}
}
pmo->scratch.pmo_dcn4.num_stutter_candidates = 0;
@@ -2179,7 +2186,7 @@ bool pmo_dcn4_fams2_init_for_stutter(struct dml2_pmo_init_for_stutter_in_out *in
pmo->scratch.pmo_dcn4.z8_vblank_optimizable = false;
}
if (pmo->soc_bb->power_management_parameters.stutter_enter_plus_exit_latency_us > 0) {
if (!stutter_optimization_too_expensive && pmo->soc_bb->power_management_parameters.stutter_enter_plus_exit_latency_us > 0) {
pmo->scratch.pmo_dcn4.optimal_vblank_reserved_time_for_stutter_us[pmo->scratch.pmo_dcn4.num_stutter_candidates] = (unsigned int)pmo->soc_bb->power_management_parameters.stutter_enter_plus_exit_latency_us;
pmo->scratch.pmo_dcn4.num_stutter_candidates++;
}