[PATCH v3 6/6] drm/v3d: Remove dedicated fence_lock

[Maíra Canal <mcanal@igalia.com>]

Commit adefb2ccea1e ("drm/v3d: create a dedicated lock for dma fence")
split `fence_lock` from `queue_lock` because v3d_job_update_stats() was
taking `queue_lock` to protect `job->file_priv` during stats collection
in the IRQ handler. Using the same lock for both DMA fence signaling and
stats protection in a IRQ context caused issues on PREEMPT_RT.

Since then, the stats infrastructure has been reworked: v3d_stats is now
refcounted and jobs hold their own references to stats objects, so
v3d_job_update_stats() no longer takes `queue_lock` at all.

With the original reason for the split gone, merge `fence_lock` back
into `queue_lock` to simplify the locking scheme.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
---
 drivers/gpu/drm/v3d/v3d_drv.h   | 2 --
 drivers/gpu/drm/v3d/v3d_fence.c | 2 +-
 drivers/gpu/drm/v3d/v3d_gem.c   | 1 -
 3 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
index 3de485abd8fc274b361cd17a00cab189d8e69643..6a3cad933439812d78da5797749c020a9bf46402 100644
--- a/drivers/gpu/drm/v3d/v3d_drv.h
+++ b/drivers/gpu/drm/v3d/v3d_drv.h
@@ -71,8 +71,6 @@ struct v3d_queue_state {
 	/* Currently active job for this queue */
 	struct v3d_job *active_job;
 	spinlock_t queue_lock;
-	/* Protect dma fence for signalling job completion */
-	spinlock_t fence_lock;
 };
 
 /* Performance monitor object. The perform lifetime is controlled by userspace
diff --git a/drivers/gpu/drm/v3d/v3d_fence.c b/drivers/gpu/drm/v3d/v3d_fence.c
index 3c999f60003c8746fba3c635efcaa7ac8c9ecb41..c500136d045572fbaa1e69877b21255c9091dcb1 100644
--- a/drivers/gpu/drm/v3d/v3d_fence.c
+++ b/drivers/gpu/drm/v3d/v3d_fence.c
@@ -15,7 +15,7 @@ struct dma_fence *v3d_fence_create(struct v3d_dev *v3d, enum v3d_queue q)
 	fence->dev = &v3d->drm;
 	fence->queue = q;
 	fence->seqno = ++queue->emit_seqno;
-	dma_fence_init(&fence->base, &v3d_fence_ops, &queue->fence_lock,
+	dma_fence_init(&fence->base, &v3d_fence_ops, &queue->queue_lock,
 		       queue->fence_context, fence->seqno);
 
 	return &fence->base;
diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index 859e63dd7e9738e3a3702edfb857ec3e844b052b..75d9eccd796664e67277c1f83ad59063f164d1da 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -296,7 +296,6 @@ v3d_gem_init(struct drm_device *dev)
 		queue->fence_context = dma_fence_context_alloc(1);
 
 		spin_lock_init(&queue->queue_lock);
-		spin_lock_init(&queue->fence_lock);
 	}
 
 	spin_lock_init(&v3d->mm_lock);

-- 
2.53.0