[PATCH 4/4] drm/i915: Implement vblank synchronized MBUS join changes

Stanislav Lisovskiy stanislav.lisovskiy at intel.com
Wed Mar 20 08:28:06 UTC 2024


Currently we can't change MBUS join status without doing a modeset,
because we are lacking mechanism to synchronize those with vblank.
However then this means that we can't do a fastset, if there is a need
to change MBUS join state. Fix that by implementing such change.
We already call correspondent check and update at pre_plane dbuf update,
so the only thing left is to have a non-modeset version of that.
If active pipes stay the same then fastset is possible and only MBUS
join state/ddb allocation updates would be committed.

v2: Implement additional changes according to BSpec.
    Vblank wait is needed after MBus/Dbuf programming in case if
    no modeset is done and we are switching from single to multiple
    displays, i.e mbus join state switches from "joined" to  "non-joined"
    state. Otherwise vblank wait is not needed according to spec.

v3: Split mbus and dbox programming into to pre/post plane update parts,
    how it should be done according to BSpec.

v4: - Place "single display to multiple displays scenario" MBUS/DBOX programming
      after DDB reallocation, but before crtc enabling(that is where is has
      to be according to spec).
    - Check if crtc is still active, not only the old state.
    - Do a vblank wait if MBUX DBOX register was modified.
    - And of course do vblank wait only if crtc was active.
    - Do vblank wait only if we are not doing a modeset, if we are doing
      something before *commit_modeset_enables, because all crtcs might be
      disabled at this moment, so we will get WARN if try waiting for vblank
      then.
    - Still getting FIFO underrun so try waiting for vblank in pre_plane update
      as well.
    - Write also pipe that we need to sync with to MBUS_CTL register.

v5: - Do vblank wait only for the first pipe, if mbus is joined
    - Check also if new/old_dbuf_state is not NULL, before getting single pipe
      and active pipes.

v6: - Add pre/post ddb call sites for doing mbus/mbox updates for switching
      between single/multiple displays(Ville Syrjälä)
    - When writing MBUS_CTL check if synced pipe is enabled, otherwise use
      PIPE_NONE sync option(Ville Syrjälä)
    - Use for_each_crtc_in_pipe_mask to go through all active pipes, not
      just ones in state, when updating mbox registers(Ville Syrjälä)
    - Improve checks for switching between multiple <=> single displays

v7: - Extract sync pipe calculation to separate function(Ville Syrjälä)
    - Removed redundant loop over crtc in post ddb call site(Ville Syrjälä)
    - Use old_dbuf_state to determine synced pipe when switching to multiple
      displays in post ddb call site(Ville Syrjälä)
    - Removed num_active_pipes checks and use joined_mbus only(Ville Syrjälä)
    - Extracted dbox update change to separate patch(Ville Syrjälä)
    - Added handling for the case, when mbus_joined state didn't change
      (Ville Syrjälä)

v8: - Removed redundant comments(Ville Syrjälä)
    - Pass dbuf_state to intel_dbuf_mbus_join_update instead of pipe(Ville Syrjälä)
    - Moved non-changed mbus_join logic from pre_plane to post_ddb hook(Ville Syrjälä)

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c |   6 +-
 drivers/gpu/drm/i915/display/skl_watermark.c | 106 +++++++++++++++----
 drivers/gpu/drm/i915/display/skl_watermark.h |   2 +
 3 files changed, 90 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index b88f214e111ae..d5351f6fa2eb4 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -6895,6 +6895,8 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
 		intel_pre_update_crtc(state, crtc);
 	}
 
+	intel_dbuf_mbus_pre_ddb_update(state);
+
 	while (update_pipes) {
 		for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
 						    new_crtc_state, i) {
@@ -6925,6 +6927,8 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
 		}
 	}
 
+	intel_dbuf_mbus_post_ddb_update(state);
+
 	update_pipes = modeset_pipes;
 
 	/*
@@ -7169,9 +7173,7 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 	}
 
 	intel_encoders_update_prepare(state);
-
 	intel_dbuf_pre_plane_update(state);
-	intel_mbus_dbox_update(state);
 
 	for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
 		if (new_crtc_state->do_async_flip)
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 2207ecd2605c2..4c1c2f558e3e7 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -4,6 +4,7 @@
  */
 
 #include <drm/drm_blend.h>
+#include <drm/drm_print.h>
 
 #include "i915_drv.h"
 #include "i915_fixed.h"
@@ -2636,13 +2637,6 @@ skl_compute_ddb(struct intel_atomic_state *state)
 		if (ret)
 			return ret;
 
-		if (old_dbuf_state->joined_mbus != new_dbuf_state->joined_mbus) {
-			/* TODO: Implement vblank synchronized MBUS joining changes */
-			ret = intel_modeset_all_pipes_late(state, "MBUS joining change");
-			if (ret)
-				return ret;
-		}
-
 		drm_dbg_kms(&i915->drm,
 			    "Enabled dbuf slices 0x%x -> 0x%x (total dbuf slices 0x%x), mbus joined? %s->%s\n",
 			    old_dbuf_state->enabled_slices,
@@ -3594,30 +3588,49 @@ static void intel_dbuf_mdclk_min_tracker_update(struct intel_atomic_state *state
 					    new_dbuf_state->joined_mbus);
 }
 
+static enum pipe intel_dbuf_get_sync_pipe(const struct intel_dbuf_state *dbuf_state)
+{
+	return ffs(dbuf_state->active_pipes) - 1;
+}
+
 /*
  * Configure MBUS_CTL and all DBUF_CTL_S of each slice to join_mbus state before
  * update the request state of all DBUS slices.
  */
-static void intel_dbuf_mbus_join_update(struct intel_atomic_state *state)
+static void intel_dbuf_mbus_join_update(struct intel_atomic_state *state,
+					const struct intel_dbuf_state *dbuf_state)
 {
 	struct drm_i915_private *i915 = to_i915(state->base.dev);
 	u32 mbus_ctl;
 	const struct intel_dbuf_state *new_dbuf_state =
 		intel_atomic_get_new_dbuf_state(state);
+	struct intel_crtc *crtc;
+	struct intel_crtc_state *new_crtc_state;
+	u32 pipe_select;
+	enum pipe sync_pipe;
 
 	if (!HAS_MBUS_JOINING(i915))
 		return;
 
+	sync_pipe = intel_dbuf_get_sync_pipe(dbuf_state);
+	crtc = intel_crtc_for_pipe(i915, sync_pipe);
+	new_crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
+
+	if (new_crtc_state && !intel_crtc_needs_modeset(new_crtc_state))
+		pipe_select = MBUS_JOIN_PIPE_SELECT(sync_pipe);
+	else
+		pipe_select = MBUS_JOIN_PIPE_SELECT_NONE;
+
 	/*
 	 * TODO: Implement vblank synchronized MBUS joining changes.
 	 * Must be properly coordinated with dbuf reprogramming.
 	 */
 	if (new_dbuf_state->joined_mbus)
 		mbus_ctl = MBUS_HASHING_MODE_1x4 | MBUS_JOIN |
-			MBUS_JOIN_PIPE_SELECT_NONE;
+			pipe_select;
 	else
 		mbus_ctl = MBUS_HASHING_MODE_2x2 |
-			MBUS_JOIN_PIPE_SELECT_NONE;
+			pipe_select;
 
 	intel_de_rmw(i915, MBUS_CTL,
 		     MBUS_HASHING_MODE_MASK | MBUS_JOIN |
@@ -3633,24 +3646,35 @@ void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
 		intel_atomic_get_old_dbuf_state(state);
 
 	if (!new_dbuf_state ||
-	    (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices &&
-	     new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus))
+	    (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices))
 		return;
 
 	WARN_ON(!new_dbuf_state->base.changed);
 
-	if ((hweight8(new_dbuf_state->active_pipes) <= hweight8(old_dbuf_state->active_pipes))
-	    || (old_dbuf_state->active_pipes == 0)) {
-		intel_dbuf_mbus_join_update(state);
-		intel_dbuf_mdclk_min_tracker_update(state);
-	}
-
 	gen9_dbuf_slices_update(i915,
 				old_dbuf_state->enabled_slices |
 				new_dbuf_state->enabled_slices);
 }
 
 void intel_dbuf_post_plane_update(struct intel_atomic_state *state)
+{
+	struct drm_i915_private *i915 = to_i915(state->base.dev);
+	const struct intel_dbuf_state *new_dbuf_state =
+		intel_atomic_get_new_dbuf_state(state);
+	const struct intel_dbuf_state *old_dbuf_state =
+		intel_atomic_get_old_dbuf_state(state);
+
+	if (!new_dbuf_state ||
+	    (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices))
+		return;
+
+	WARN_ON(!new_dbuf_state->base.changed);
+
+	gen9_dbuf_slices_update(i915,
+				new_dbuf_state->enabled_slices);
+}
+
+void intel_dbuf_mbus_pre_ddb_update(struct intel_atomic_state *state)
 {
 	struct drm_i915_private *i915 = to_i915(state->base.dev);
 	const struct intel_dbuf_state *new_dbuf_state =
@@ -3665,13 +3689,51 @@ void intel_dbuf_post_plane_update(struct intel_atomic_state *state)
 
 	WARN_ON(!new_dbuf_state->base.changed);
 
-	if (hweight8(new_dbuf_state->active_pipes) > hweight8(old_dbuf_state->active_pipes)) {
-		intel_dbuf_mbus_join_update(state);
+	if (!old_dbuf_state->joined_mbus && new_dbuf_state->joined_mbus) {
+		drm_WARN_ON(&i915->drm, !is_power_of_2(new_dbuf_state->active_pipes));
+
+		intel_dbuf_mbus_join_update(state, new_dbuf_state);
+		intel_mbus_dbox_update(state);
 		intel_dbuf_mdclk_min_tracker_update(state);
 	}
+}
 
-	gen9_dbuf_slices_update(i915,
-				new_dbuf_state->enabled_slices);
+void intel_dbuf_mbus_post_ddb_update(struct intel_atomic_state *state)
+{
+	struct drm_i915_private *i915 = to_i915(state->base.dev);
+	const struct intel_dbuf_state *new_dbuf_state =
+		intel_atomic_get_new_dbuf_state(state);
+	const struct intel_dbuf_state *old_dbuf_state =
+		intel_atomic_get_old_dbuf_state(state);
+
+	if (new_dbuf_state && old_dbuf_state &&
+	    new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus) {
+		intel_dbuf_mdclk_min_tracker_update(state);
+		intel_mbus_dbox_update(state);
+	}
+
+	if (!new_dbuf_state ||
+	    (new_dbuf_state->enabled_slices == old_dbuf_state->enabled_slices &&
+	     new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus))
+		return;
+
+	WARN_ON(!new_dbuf_state->base.changed);
+
+	if (old_dbuf_state->joined_mbus && !new_dbuf_state->joined_mbus) {
+		enum pipe sync_pipe = intel_dbuf_get_sync_pipe(old_dbuf_state);
+		struct intel_crtc *crtc = intel_crtc_for_pipe(i915, sync_pipe);
+		struct intel_crtc_state *new_crtc_state =
+				intel_atomic_get_new_crtc_state(state, crtc);
+
+		drm_WARN_ON(&i915->drm, is_power_of_2(new_dbuf_state->active_pipes));
+
+		intel_dbuf_mdclk_min_tracker_update(state);
+		intel_mbus_dbox_update(state);
+		intel_dbuf_mbus_join_update(state, old_dbuf_state);
+
+		if (new_crtc_state && !intel_crtc_needs_modeset(new_crtc_state))
+			intel_crtc_wait_for_next_vblank(crtc);
+	}
 }
 
 static bool xelpdp_is_only_pipe_per_dbuf_bank(enum pipe pipe, u8 active_pipes)
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h
index 3a90741cab06a..f6d38b41e3a6c 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.h
+++ b/drivers/gpu/drm/i915/display/skl_watermark.h
@@ -77,6 +77,8 @@ int intel_dbuf_state_set_mdclk_cdclk_ratio(struct intel_atomic_state *state, u8
 void intel_dbuf_pre_plane_update(struct intel_atomic_state *state);
 void intel_dbuf_post_plane_update(struct intel_atomic_state *state);
 void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915, u8 ratio, bool joined_mbus);
+void intel_dbuf_mbus_pre_ddb_update(struct intel_atomic_state *state);
+void intel_dbuf_mbus_post_ddb_update(struct intel_atomic_state *state);
 void intel_mbus_dbox_update(struct intel_atomic_state *state);
 
 #endif /* __SKL_WATERMARK_H__ */
-- 
2.37.3



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