Blocking in a worker is ok, that's what the unbound_wq is for. And it
unifies the paths between the blocking and nonblocking commit, giving
me just one path where I have to implement the deadlock avoidance
trickery in the next patch.
I first tried to implement the following patch without this rework, but
force-completing i915_sw_fence creates some serious challenges around
properly cleaning things up. So wasn't a feasible short-term approach.
Another approach would be to simple keep track of all pending atomic
commit work items and manually queue them from the reset code. With the
caveat that double-queue in case we race with the i915_sw_fence must be
avoided. Given all that, taking the cost of a double schedule in atomic
for the short-term fix is the best approach, but can be changed in the
future of course.
v2: Amend commit message (Chris).
v3: Add comment explaining why we do nothing in the sw_fence complete
callback (Michel).
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> (v2)
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b2c220ba2575..da8d0d3b2bc2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12082,6 +12082,8 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
unsigned crtc_vblank_mask = 0;
int i;
+ i915_sw_fence_wait(&intel_state->commit_ready);
+
drm_atomic_helper_wait_for_dependencies(state);
if (intel_state->modeset)
@@ -12247,10 +12249,8 @@ intel_atomic_commit_ready(struct i915_sw_fence *fence,
switch (notify) {
case FENCE_COMPLETE:
- if (state->base.commit_work.func)
- queue_work(system_unbound_wq, &state->base.commit_work);
+ /* we do blocking waits in the worker, nothing to do here */
break;
-
case FENCE_FREE:
{
struct intel_atomic_helper *helper =
@@ -12352,14 +12352,14 @@ static int intel_atomic_commit(struct drm_device *dev,
}
drm_atomic_state_get(state);
- INIT_WORK(&state->commit_work,
- nonblock ? intel_atomic_commit_work : NULL);
+ INIT_WORK(&state->commit_work, intel_atomic_commit_work);
i915_sw_fence_commit(&intel_state->commit_ready);
- if (!nonblock) {
- i915_sw_fence_wait(&intel_state->commit_ready);
+ if (nonblock)
+ queue_work(system_unbound_wq, &state->commit_work);
+ else
intel_atomic_commit_tail(state);
- }
+
return 0;
}
--
2.13.3
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