[PATCH 2/2] drm/i915: Implement vblank synchronized MBUS join changes
Stanislav Lisovskiy
stanislav.lisovskiy at intel.com
Tue Aug 29 12:53:09 UTC 2023
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.
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
Tested-by: Khaled Almahallawy <khaled.almahallawy at intel.com>
---
drivers/gpu/drm/i915/display/intel_display.c | 8 ++-
drivers/gpu/drm/i915/display/skl_watermark.c | 74 ++++++++++++++++----
drivers/gpu/drm/i915/display/skl_watermark.h | 1 +
3 files changed, 66 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index f6397462e4c25..c6fdf008c8d27 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -6737,6 +6737,12 @@ static void skl_commit_modeset_enables(struct intel_atomic_state *state)
}
}
+ /*
+ * Some MBUS/DBuf update scenarios require that changes are done _after_ DDB
+ * reallocation, but _before_ crtc enabling.
+ */
+ intel_dbuf_mbus_post_ddb_update(state);
+
update_pipes = modeset_pipes;
/*
@@ -6996,9 +7002,7 @@ 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..aa4ac50b029d3 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 |
@@ -3547,13 +3547,47 @@ 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_update(state);
-
gen9_dbuf_slices_update(i915,
new_dbuf_state->enabled_slices);
}
+void intel_dbuf_mbus_post_ddb_update(struct intel_atomic_state *state)
+{
+ 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 &&
+ new_dbuf_state->joined_mbus == old_dbuf_state->joined_mbus))
+ return;
+
+ WARN_ON(!new_dbuf_state->base.changed);
+
+ /*
+ * 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, *new_crtc_state;
+ int i;
+ intel_dbuf_mbus_update(state);
+ intel_mbus_dbox_update(state);
+
+ for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
+ new_crtc_state, i) {
+ /*
+ * According to BSpec we should wait vblank on previously single display
+ */
+ if (!old_crtc_state->hw.active || !new_crtc_state->hw.active)
+ continue;
+
+ intel_crtc_wait_for_next_vblank(crtc);
+ }
+ }
+}
+
static bool xelpdp_is_only_pipe_per_dbuf_bank(enum pipe pipe, u8 active_pipes)
{
switch (pipe) {
@@ -3577,8 +3611,8 @@ void intel_mbus_dbox_update(struct intel_atomic_state *state)
{
struct drm_i915_private *i915 = to_i915(state->base.dev);
const struct intel_dbuf_state *new_dbuf_state, *old_dbuf_state;
- const struct intel_crtc_state *new_crtc_state;
- const struct intel_crtc *crtc;
+ const struct intel_crtc_state *new_crtc_state, *old_crtc_state;
+ struct intel_crtc *crtc;
u32 val = 0;
int i;
@@ -3624,12 +3658,14 @@ void intel_mbus_dbox_update(struct intel_atomic_state *state)
val |= MBUS_DBOX_B_CREDIT(8);
}
- for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
- u32 pipe_val = val;
+ for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+ u32 pipe_val = val, old_pipe_val;
if (!new_crtc_state->hw.active)
continue;
+ old_pipe_val = intel_de_read(i915, PIPE_MBUS_DBOX_CTL(crtc->pipe));
+
if (DISPLAY_VER(i915) >= 14) {
if (xelpdp_is_only_pipe_per_dbuf_bank(crtc->pipe,
new_dbuf_state->active_pipes))
@@ -3639,6 +3675,14 @@ void intel_mbus_dbox_update(struct intel_atomic_state *state)
}
intel_de_write(i915, PIPE_MBUS_DBOX_CTL(crtc->pipe), pipe_val);
+
+ /*
+ * BSpec instructs us to wait for vblank, if credits were changed.
+ * However we need to do that here only if crtc was active prior to change.
+ */
+ if (old_pipe_val != pipe_val &&
+ old_crtc_state->hw.active && !state->modeset)
+ intel_crtc_wait_for_next_vblank(crtc);
}
}
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h
index f91a3d4ddc075..96a4eed1daceb 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.h
+++ b/drivers/gpu/drm/i915/display/skl_watermark.h
@@ -71,6 +71,7 @@ intel_atomic_get_dbuf_state(struct intel_atomic_state *state);
int intel_dbuf_init(struct drm_i915_private *i915);
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_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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