[PATCH v5 2/5] drm/i915/psr: Calculate aux less wake time

[Jouni Högander]

Calculate aux less wake time and store it into alpm_params struct

Bspec: 71477

v4:
  - re-use fast_wake_lines to store aux_less_wake_lines
v3:
  - use ALPM_CTL_AUX_LESS_WAKE_TIME_MASK instead of value 63
v2:
  - use variables instead of values directly
  - fix max value
  - move converting port clock to Mhz into _lnl_compute_aux_less_wake_time

Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 60 ++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 3f35572354ba..bfe320bcefef 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1126,6 +1126,63 @@ static bool _compute_psr2_sdp_prior_scanline_indication(struct intel_dp *intel_d
 	return true;
 }
 
+/*
+ * AUX-Less Wake Time = CEILING( ((PHY P2 to P0) + tLFPS_Period, Max+
+ * tSilence, Max+ tPHY Establishment + tCDS) / tline)
+ * For the "PHY P2 to P0" latency see the PHY Power Control page
+ * (PHY P2 to P0) : https://gfxspecs.intel.com/Predator/Home/Index/68965
+ * : 12 us
+ * The tLFPS_Period, Max term is 800ns
+ * The tSilence, Max term is 180ns
+ * The tPHY Establishment (a.k.a. t1) term is 50us
+ * The tCDS term is 1 or 2 times t2
+ * t2 = Number ML_PHY_LOCK * tML_PHY_LOCK
+ * Number ML_PHY_LOCK = ( 7 + CEILING( 6.5us / tML_PHY_LOCK ) + 1)
+ * Rounding up the 6.5us padding to the next ML_PHY_LOCK boundary and
+ * adding the "+ 1" term ensures all ML_PHY_LOCK sequences that start
+ * within the CDS period complete within the CDS period regardless of
+ * entry into the period
+ * tML_PHY_LOCK = TPS4 Length * ( 10 / (Link Rate in MHz) )
+ * TPS4 Length = 252 Symbols
+ */
+static int _lnl_compute_aux_less_wake_time(int port_clock)
+{
+	int tphy2_p2_to_p0 = 12 * 1000;
+	int tlfps_period_max = 800;
+	int tsilence_max = 180;
+	int t1 = 50 * 1000;
+	int tps4 = 252;
+	int tml_phy_lock = 1000 * 1000 * tps4 * 10 / port_clock;
+	int num_ml_phy_lock = 7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1;
+	int t2 = num_ml_phy_lock * tml_phy_lock;
+	int tcds = 1 * t2;
+
+	return DIV_ROUND_UP(tphy2_p2_to_p0 + tlfps_period_max + tsilence_max +
+			    t1 + tcds, 1000);
+}
+
+static int _lnl_compute_aux_less_alpm_params(struct intel_dp *intel_dp,
+					     struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	int aux_less_wake_time, aux_less_wake_lines;
+
+	aux_less_wake_time =
+		_lnl_compute_aux_less_wake_time(crtc_state->port_clock);
+	aux_less_wake_lines = intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode,
+						       aux_less_wake_time);
+
+	if (aux_less_wake_lines > ALPM_CTL_AUX_LESS_WAKE_TIME_MASK)
+		return false;
+
+	if (i915->display.params.psr_safest_params)
+		aux_less_wake_lines = ALPM_CTL_AUX_LESS_WAKE_TIME_MASK;
+
+	intel_dp->psr.alpm_parameters.fast_wake_lines = aux_less_wake_lines;
+
+	return true;
+}
+
 static bool _lnl_compute_alpm_params(struct intel_dp *intel_dp,
 				     struct intel_crtc_state *crtc_state)
 {
@@ -1142,6 +1199,9 @@ static bool _lnl_compute_alpm_params(struct intel_dp *intel_dp,
 	if (check_entry_lines > 15)
 		return false;
 
+	if (!_lnl_compute_aux_less_alpm_params(intel_dp, crtc_state))
+		return false;
+
 	if (i915->display.params.psr_safest_params)
 		check_entry_lines = 15;
 
-- 
2.34.1