[Intel-gfx] [PATCH] drm/i915/display: Support PSR entry VSC packet to be transmitted one frame earlier

[Mika Kahola]

Display driver shall read DPCD 00071h[3:1] during configuration
to get PSR setup time. This register provides the setup time
requirement on the VSC SDP entry packet. If setup time cannot be
met with the current timings
(e.g., PSR setup time + other blanking requirements > blanking time),
driver should enable sending VSC SDP one frame earlier before sending
the capture frame.

BSpec: 69895 (PSR Entry Setup Frames 17:16)

Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_psr.c      | 35 ++++++++++++++++---
 drivers/gpu/drm/i915/display/intel_psr_regs.h |  2 ++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 65ea37fe8cff..a0bcab6f2bec 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1710,6 +1710,7 @@ struct intel_psr {
 	u32 dc3co_exitline;
 	u32 dc3co_exit_delay;
 	struct delayed_work dc3co_work;
+	u8 entry_setup_frames;
 };
 
 struct intel_dp {
diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 4f1f31fc9529..0acb4edae128 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -592,6 +592,9 @@ static void intel_psr_enable_sink(struct intel_dp *intel_dp)
 	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
 		dpcd_val |= DP_PSR_SU_REGION_SCANLINE_CAPTURE;
 
+	if (intel_dp->psr.entry_setup_frames > 0)
+		dpcd_val |= DP_PSR_FRAME_CAPTURE;
+
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, dpcd_val);
 
 	drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
@@ -690,6 +693,9 @@ static void hsw_activate_psr1(struct intel_dp *intel_dp)
 	if (DISPLAY_VER(dev_priv) >= 8)
 		val |= EDP_PSR_CRC_ENABLE;
 
+	if (intel_dp->psr.entry_setup_frames > 0)
+		val |= EDP_PSR_ENTRY_SETUP_FRAMES(intel_dp->psr.entry_setup_frames);
+
 	intel_de_rmw(dev_priv, psr_ctl_reg(dev_priv, cpu_transcoder),
 		     ~EDP_PSR_RESTORE_PSR_ACTIVE_CTX_MASK, val);
 }
@@ -731,6 +737,7 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 {
 	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
 	enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
+	u8 frames_before_su_entry;
 	u32 val = EDP_PSR2_ENABLE;
 
 	val |= EDP_PSR2_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
@@ -741,7 +748,10 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 	if (DISPLAY_VER(dev_priv) >= 10 && DISPLAY_VER(dev_priv) <= 12)
 		val |= EDP_Y_COORDINATE_ENABLE;
 
-	val |= EDP_PSR2_FRAME_BEFORE_SU(max_t(u8, intel_dp->psr.sink_sync_latency + 1, 2));
+	frames_before_su_entry = max_t(u8,
+				       intel_dp->psr.sink_sync_latency + 1,
+				       2);
+	val |= EDP_PSR2_FRAME_BEFORE_SU(frames_before_su_entry);
 	val |= intel_psr2_get_tp_time(intel_dp);
 
 	if (DISPLAY_VER(dev_priv) >= 12) {
@@ -785,6 +795,14 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
 		val |= EDP_PSR2_SU_SDP_SCANLINE;
 
+	/* Entry setup frames must be at least 1 less than frames before SU entry */
+	if (intel_dp->psr.entry_setup_frames > 0) {
+		val |= EDP_PSR_ENTRY_SETUP_FRAMES(intel_dp->psr.entry_setup_frames);
+
+		if (intel_dp->psr.entry_setup_frames >= frames_before_su_entry)
+			val |= EDP_PSR2_FRAME_BEFORE_SU(frames_before_su_entry + 1);
+	}
+
 	if (intel_dp->psr.psr2_sel_fetch_enabled) {
 		u32 tmp;
 
@@ -1252,10 +1270,17 @@ void intel_psr_compute_config(struct intel_dp *intel_dp,
 
 	if (intel_usecs_to_scanlines(adjusted_mode, psr_setup_time) >
 	    adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vdisplay - 1) {
-		drm_dbg_kms(&dev_priv->drm,
-			    "PSR condition failed: PSR setup time (%d us) too long\n",
-			    psr_setup_time);
-		return;
+		if (DISPLAY_VER(dev_priv) >= 20) {
+			intel_dp->psr.entry_setup_frames = 1;
+			drm_dbg_kms(&dev_priv->drm,
+				    "PSR setup entry frames: %d\n",
+				    intel_dp->psr.entry_setup_frames);
+		} else {
+			drm_dbg_kms(&dev_priv->drm,
+				    "PSR condition failed: PSR setup time (%d us) too long\n",
+				    psr_setup_time);
+			return;
+		}
 	}
 
 	crtc_state->has_psr = true;
diff --git a/drivers/gpu/drm/i915/display/intel_psr_regs.h b/drivers/gpu/drm/i915/display/intel_psr_regs.h
index d39951383c92..9414c4de5f6e 100644
--- a/drivers/gpu/drm/i915/display/intel_psr_regs.h
+++ b/drivers/gpu/drm/i915/display/intel_psr_regs.h
@@ -35,6 +35,8 @@
 #define   EDP_PSR_MIN_LINK_ENTRY_TIME_0_LINES	REG_FIELD_PREP(EDP_PSR_MIN_LINK_ENTRY_TIME_MASK, 3)
 #define   EDP_PSR_MAX_SLEEP_TIME_MASK		REG_GENMASK(24, 20)
 #define   EDP_PSR_MAX_SLEEP_TIME(x)		REG_FIELD_PREP(EDP_PSR_MAX_SLEEP_TIME_MASK, (x))
+#define   EDP_PSR_ENTRY_SETUP_FRAMES_MASK	REG_GENMASK(17, 16)
+#define   EDP_PSR_ENTRY_SETUP_FRAMES(x)		REG_FIELD_PREP(EDP_PSR_ENTRY_SETUP_FRAMES_MASK, (x))
 #define   EDP_PSR_SKIP_AUX_EXIT			REG_BIT(12)
 #define   EDP_PSR_TP_MASK			REG_BIT(11)
 #define   EDP_PSR_TP_TP1_TP2			REG_FIELD_PREP(EDP_PSR_TP_MASK, 0)
-- 
2.34.1