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.

Signed-off-by: Stanislav Lisovskiy <[email protected]>
Tested-by: Khaled Almahallawy <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_display.c |  2 --
 drivers/gpu/drm/i915/display/skl_watermark.c | 36 +++++++++++++++-----
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c 
b/drivers/gpu/drm/i915/display/intel_display.c
index 8c81206ce90d7..249ba955cce2a 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7041,9 +7041,7 @@ 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 af99f2abd8446..b5c5fa9ecf43c 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2614,13 +2614,6 @@ 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(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,
@@ -3524,8 +3517,15 @@ void intel_dbuf_pre_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))
+       /*
+        * Switching from multiple to single display scenario.
+        * Also we put here "<=" instead of "<" for suboptimal cases, when
+        * we switch from single => single display, enabling mbus join.
+        */
+       if (hweight8(new_dbuf_state->active_pipes) <= 
hweight8(old_dbuf_state->active_pipes)) {
                intel_dbuf_mbus_update(state);
+               intel_mbus_dbox_update(state);
+       }
 
        gen9_dbuf_slices_update(i915,
                                old_dbuf_state->enabled_slices |
@@ -3547,8 +3547,26 @@ 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))
+       /*
+        * Switching from single to multiple display scenario
+        */
+       if (hweight8(new_dbuf_state->active_pipes) > 
hweight8(old_dbuf_state->active_pipes)) {
+               struct intel_crtc *crtc;
+               struct intel_crtc_state *old_crtc_state;
+               int i;
                intel_dbuf_mbus_update(state);
+               intel_mbus_dbox_update(state);
+
+               for_each_old_intel_crtc_in_state(state, crtc, old_crtc_state, 
i) {
+                       /*
+                        * According to BSpec we should wait vblank on 
previously single display
+                        */
+                       if (!old_crtc_state->hw.active)
+                               continue;
+
+                       intel_crtc_wait_for_next_vblank(crtc);
+               }
+       }
 
        gen9_dbuf_slices_update(i915,
                                new_dbuf_state->enabled_slices);
-- 
2.37.3

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