[PATCH 04/11] drm/vc4: Return the seqno of the submitted job

[Maíra Canal]

VC4_SUBMIT_CL reports the seqno of the job it queued by re-reading
vc4->emit_seqno once vc4_queue_submit() has returned. That counter is
shared by every submission on the device, so a job queued by another
thread in the meantime bumps it first and the ioctl hands userspace a
seqno belonging to a job it did not submit. Waiting on that seqno means
waiting for unrelated work.

Now that the submit path holds a reference to `exec` until it is done
with the job, report the seqno recorded in it.

Fixes: d5b1a78a772f ("drm/vc4: Add support for drawing 3D frames.")
Signed-off-by: Maíra Canal <mca...@igalia.com>
---
 drivers/gpu/drm/vc4/vc4_gem.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index b56952bb6b97..9cf343297f83 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -620,7 +620,6 @@ vc4_queue_submit(struct drm_device *dev, struct 
vc4_exec_info *exec,
 {
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_exec_info *renderjob;
-       uint64_t seqno;
        unsigned long irqflags;
        struct vc4_fence *fence;
 
@@ -631,8 +630,7 @@ vc4_queue_submit(struct drm_device *dev, struct 
vc4_exec_info *exec,
 
        spin_lock_irqsave(&vc4->job_lock, irqflags);
 
-       seqno = ++vc4->emit_seqno;
-       exec->seqno = seqno;
+       exec->seqno = ++vc4->emit_seqno;
 
        dma_fence_init(&fence->base, &vc4_fence_ops, &vc4->job_lock,
                       vc4->dma_fence_context, exec->seqno);
@@ -1170,7 +1168,7 @@ vc4_submit_cl_ioctl(struct drm_device *dev, void *data,
                goto fail_unreserve;
 
        /* Return the seqno for our job. */
-       args->seqno = vc4->emit_seqno;
+       args->seqno = exec->seqno;
 
        vc4_exec_put(exec);
 

-- 
2.55.0