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.
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/skl_watermark.c | 36 ++++++++++++++++----
1 file changed, 29 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 063929a42a42f..4fbc74e800217 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,
@@ -3528,6 +3521,35 @@ void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
gen9_dbuf_slices_update(i915,
old_dbuf_state->enabled_slices |
new_dbuf_state->enabled_slices);
+
+ /*
+ * If we are not doing a modeset, that means we must synchronize
+ * our MBUS configuration changes with vblank.
+ * According to MBus programming section of BSpec, we must wait for vblank
+ * on active crtc, which was single display, when switching from single
+ * display(mbus joined) to additional multiple displays(mbus not joined)
+ * after Mbus/Dbuf slice programming is done.
+ */
+ if (!state->modeset && !new_dbuf_state->joined_mbus && old_dbuf_state->joined_mbus) {
+ struct intel_crtc *crtc;
+ struct intel_crtc_state *new_crtc_state, *old_crtc_state;
+ int i;
+
+ for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+ /*
+ * Need to wait for vblank only if crtc was active prior to that change,
+ * i.e this is a scenario when we switch from single display to multiple
+ * displays, without doing a full modeset and it still stays on, according
+ * to BSpec only in that case we need to wait for vblank on that previously
+ * single display. Otherwise no wait is needed. Rest of the cases, are not
+ * possible without a modeset anyway.
+ */
+ if (!new_crtc_state->hw.active || !old_crtc_state->hw.active)
+ continue;
+
+ intel_crtc_wait_for_next_vblank(crtc);
+ }
+ }
}
void intel_dbuf_post_plane_update(struct intel_atomic_state *state)
--
2.37.3
