[PATCH 3/4] drm/i915/display/psr: Use continuos full frame to handle frontbuffer invalidations

José Roberto de Souza jose.souza at intel.com
Fri Apr 1 13:38:49 UTC 2022


Instead of exit PSR when a frontbuffer invalidation happens, we can
enable the PSR2 selective fetch continuous full frame, that will keep
the panel updated like PSR was disabled but without keeping PSR active.

So as soon as the frontbuffer flush happens we can disable the
continuous full frame and start to do selective fetches much quicker
than the path that would enable PSR, that will wait a few frames
to actually activate PSR.

Also this approach has proven to fix some glitches found in Alderlake-P
when there are a lot of invalidations happening together with page
flips.

Some may ask why it is writing to CURSURFLIVE(), it is because
that is the way that hardware team provided us to poke display to
handle PSR updates, and it is being used since display 9.

v2:
- handling possible race conditions between frontbuffer rendering and
page flips

Cc: Khaled Almahallawy <khaled.almahallawy at intel.com>
Cc: Shawn C Lee <shawn.c.lee at intel.com>
Cc: Jouni Högander <jouni.hogander at intel.com>
Cc: Mika Kahola <mika.kahola at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 +
 drivers/gpu/drm/i915/display/intel_psr.c      | 88 ++++++++++++++++---
 2 files changed, 77 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 96024f7d839d4..cfd042117b109 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1525,6 +1525,7 @@ struct intel_psr {
 	bool colorimetry_support;
 	bool psr2_enabled;
 	bool psr2_sel_fetch_enabled;
+	bool psr2_sel_fetch_cff_enabled;
 	bool req_psr2_sdp_prior_scanline;
 	u8 sink_sync_latency;
 	ktime_t last_entry_attempt;
diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 58597480054eb..5b1963b7743dc 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1221,6 +1221,7 @@ static void intel_psr_enable_locked(struct intel_dp *intel_dp,
 	intel_dp->psr.dc3co_exit_delay = val;
 	intel_dp->psr.dc3co_exitline = crtc_state->dc3co_exitline;
 	intel_dp->psr.psr2_sel_fetch_enabled = crtc_state->enable_psr2_sel_fetch;
+	intel_dp->psr.psr2_sel_fetch_cff_enabled = false;
 	intel_dp->psr.req_psr2_sdp_prior_scanline =
 		crtc_state->req_psr2_sdp_prior_scanline;
 
@@ -1455,6 +1456,13 @@ static inline u32 man_trk_ctl_partial_frame_bit_get(struct drm_i915_private *dev
 	       PSR2_MAN_TRK_CTL_SF_PARTIAL_FRAME_UPDATE;
 }
 
+static inline u32 man_trk_ctl_continuos_full_frame(struct drm_i915_private *dev_priv)
+{
+	return IS_ALDERLAKE_P(dev_priv) ?
+	       ADLP_PSR2_MAN_TRK_CTL_SF_CONTINUOS_FULL_FRAME :
+	       PSR2_MAN_TRK_CTL_SF_CONTINUOS_FULL_FRAME;
+}
+
 static void psr_force_hw_tracking_exit(struct intel_dp *intel_dp)
 {
 	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
@@ -1558,6 +1566,8 @@ void intel_psr2_program_trans_man_trk_ctl(const struct intel_crtc_state *crtc_st
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
 		lockdep_assert_held(&intel_dp->psr.lock);
+		if (intel_dp->psr.psr2_sel_fetch_cff_enabled)
+			return;
 		break;
 	}
 
@@ -2135,6 +2145,27 @@ static void intel_psr_work(struct work_struct *work)
 	mutex_unlock(&intel_dp->psr.lock);
 }
 
+static void _psr_invalidate_handle(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+
+	if (intel_dp->psr.psr2_sel_fetch_enabled) {
+		u32 val;
+
+		if (intel_dp->psr.psr2_sel_fetch_cff_enabled)
+			return;
+
+		val = man_trk_ctl_enable_bit_get(dev_priv) |
+		      man_trk_ctl_partial_frame_bit_get(dev_priv) |
+		      man_trk_ctl_continuos_full_frame(dev_priv);
+		intel_de_write(dev_priv, PSR2_MAN_TRK_CTL(intel_dp->psr.transcoder), val);
+		intel_de_write(dev_priv, CURSURFLIVE(intel_dp->psr.pipe), 0);
+		intel_dp->psr.psr2_sel_fetch_cff_enabled = true;
+	} else {
+		intel_psr_exit(intel_dp);
+	}
+}
+
 /**
  * intel_psr_invalidate - Invalidade PSR
  * @dev_priv: i915 device
@@ -2171,7 +2202,7 @@ void intel_psr_invalidate(struct drm_i915_private *dev_priv,
 		intel_dp->psr.busy_frontbuffer_bits |= pipe_frontbuffer_bits;
 
 		if (pipe_frontbuffer_bits)
-			intel_psr_exit(intel_dp);
+			_psr_invalidate_handle(intel_dp);
 
 		mutex_unlock(&intel_dp->psr.lock);
 	}
@@ -2203,6 +2234,42 @@ tgl_dc3co_flush_locked(struct intel_dp *intel_dp, unsigned int frontbuffer_bits,
 			 intel_dp->psr.dc3co_exit_delay);
 }
 
+static void _psr_flush_handle(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+
+	if (intel_dp->psr.psr2_sel_fetch_enabled) {
+		if (intel_dp->psr.psr2_sel_fetch_cff_enabled) {
+			/* can we turn CFF off? */
+			if (intel_dp->psr.busy_frontbuffer_bits == 0) {
+				u32 val = man_trk_ctl_enable_bit_get(dev_priv) |
+					  man_trk_ctl_partial_frame_bit_get(dev_priv) |
+					  man_trk_ctl_single_full_frame_bit_get(dev_priv);
+
+				/*
+				 * turn continuous full frame off and do a single
+				 * full frame
+				 */
+				intel_de_write(dev_priv, PSR2_MAN_TRK_CTL(intel_dp->psr.transcoder),
+					       val);
+				intel_de_write(dev_priv, CURSURFLIVE(intel_dp->psr.pipe), 0);
+				intel_dp->psr.psr2_sel_fetch_cff_enabled = false;
+			}
+		} else {
+			/*
+			 * continuous full frame is disabled, only a single full
+			 * frame is required
+			 */
+			psr_force_hw_tracking_exit(intel_dp);
+		}
+	} else {
+		psr_force_hw_tracking_exit(intel_dp);
+
+		if (!intel_dp->psr.active && !intel_dp->psr.busy_frontbuffer_bits)
+			schedule_work(&intel_dp->psr.work);
+	}
+}
+
 /**
  * intel_psr_flush - Flush PSR
  * @dev_priv: i915 device
@@ -2240,25 +2307,22 @@ void intel_psr_flush(struct drm_i915_private *dev_priv,
 		 * we have to ensure that the PSR is not activated until
 		 * intel_psr_resume() is called.
 		 */
-		if (intel_dp->psr.paused) {
-			mutex_unlock(&intel_dp->psr.lock);
-			continue;
-		}
+		if (intel_dp->psr.paused)
+			goto unlock;
 
 		if (origin == ORIGIN_FLIP ||
 		    (origin == ORIGIN_CURSOR_UPDATE &&
 		     !intel_dp->psr.psr2_sel_fetch_enabled)) {
 			tgl_dc3co_flush_locked(intel_dp, frontbuffer_bits, origin);
-			mutex_unlock(&intel_dp->psr.lock);
-			continue;
+			goto unlock;
 		}
 
-		/* By definition flush = invalidate + flush */
-		if (pipe_frontbuffer_bits)
-			psr_force_hw_tracking_exit(intel_dp);
+		if (pipe_frontbuffer_bits == 0)
+			goto unlock;
 
-		if (!intel_dp->psr.active && !intel_dp->psr.busy_frontbuffer_bits)
-			schedule_work(&intel_dp->psr.work);
+		/* By definition flush = invalidate + flush */
+		_psr_flush_handle(intel_dp);
+unlock:
 		mutex_unlock(&intel_dp->psr.lock);
 	}
 }
-- 
2.35.1



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