[PATCH 3/4] drm/i915/alpm: Calculate ALPM Entry check

[Jouni Högander]

ALPM Entry Check represents the number of lines needed to put the main link
to sleep and keep it in the sleep state before it can be taken out of the
SLEEP state (eDP requires the main link to be in the SLEEP state for a
minimum of 5us).

Bspec: 71477

Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  3 ++
 drivers/gpu/drm/i915/display/intel_psr.c      | 28 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 78473c99b869..f696c0f58f0a 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1681,6 +1681,9 @@ struct intel_pps {
 struct alpm_parameters {
 	u8 io_wake_lines;
 	u8 fast_wake_lines;
+
+	/* LNL and beyond */
+	u8 check_entry_lines;
 };
 
 struct intel_psr {
diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 8b1c2a1c7e94..df60b4fb0d65 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1102,6 +1102,28 @@ static bool _compute_psr2_sdp_prior_scanline_indication(struct intel_dp *intel_d
 	return true;
 }
 
+static bool _lnl_compute_alpm_params(struct intel_dp *intel_dp,
+				     struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	struct alpm_parameters *alpm_params = &intel_dp->psr.alpm_params;
+	int check_entry_lines;
+
+	/* ALPM Entry Check = 2 + CEILING( 5us /tline ) */
+	check_entry_lines = 2 +
+		intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode, 5);
+
+	if (check_entry_lines > 15)
+		return false;
+
+	if (i915->display.params.psr_safest_params)
+		check_entry_lines = 15;
+
+	alpm_params->check_entry_lines = check_entry_lines;
+
+	return true;
+}
+
 static bool _compute_alpm_params(struct intel_dp *intel_dp,
 				 struct intel_crtc_state *crtc_state)
 {
@@ -1117,6 +1139,8 @@ static bool _compute_alpm_params(struct intel_dp *intel_dp,
 		 * it is not enough -> use 45 us.
 		 */
 		fast_wake_time = 45;
+
+		/* TODO: Check how we can use ALPM_CTL fast wake extended field */
 		max_wake_lines = 12;
 	} else {
 		io_wake_time = 50;
@@ -1133,6 +1157,10 @@ static bool _compute_alpm_params(struct intel_dp *intel_dp,
 	    fast_wake_lines > max_wake_lines)
 		return false;
 
+	if (DISPLAY_VER(i915) >= 20 && !_lnl_compute_alpm_params(intel_dp,
+								 crtc_state))
+		return false;
+
 	if (i915->display.params.psr_safest_params)
 		io_wake_lines = fast_wake_lines = max_wake_lines;
 
-- 
2.34.1