On 8/7/2017 8:33 AM, Daniel Vetter wrote:
On Thu, Aug 03, 2017 at 12:44:40PM -0700, Michel Thierry wrote:
On 7/20/2017 10:57 AM, Daniel Vetter wrote:
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).
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_display.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 995522e40ec1..f6bd6282d7f7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12394,6 +12394,8 @@ 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)
@@ -12561,10 +12563,7 @@ 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);
I would add a small comment here, because later-on if someone has doubts
(and use git-blame), it won't be visible that something changed (the case
and break were added by the same commit).
Hm, not sure what comment I should put here? Suggestions? Only thing I
could come up with was
/* we do blocking waits in the worker, nothing to do here */
But not sure that adds the information you're looking for.
That sounds good to me, or maybe
"any blocking waits already handled in the worker"
But I think both are ok.
-Michel
break;
-
case FENCE_FREE:
{
struct intel_atomic_helper *helper =
@@ -12668,14 +12667,14 @@ 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;
}
Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx>
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