From: Dillon Varone dillon.varone@amd.com

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.

Cc: stable@vger.kernel.org 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 --- .../dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c b/drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c index 5a09dd298e6f..92269f0e50ed 100644 --- a/drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c +++ b/drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_pmo/dml2_pmo_dcn4_fams2.c @@ -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 @@ -2140,6 +2141,7 @@ 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; @@ -2161,10 +2163,15 @@ 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; @@ -2180,7 +2187,7 @@ 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++; }