[PATCH v3 08/11] drm/xe: Add xe_tlb_inval_idle helper

[Matthew Brost <matthew.brost@intel.com>]

Introduce the xe_tlb_inval_idle helper to detect whether any TLB
invalidations are currently in flight. This is used in context-based TLB
invalidations to determine whether dummy TLB invalidations need to be
sent to maintain proper TLB invalidation fence ordering..

v2:
 - Implement xe_tlb_inval_idle based on pending list

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
---
 drivers/gpu/drm/xe/xe_tlb_inval.c | 21 +++++++++++++++++++++
 drivers/gpu/drm/xe/xe_tlb_inval.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_tlb_inval.c b/drivers/gpu/drm/xe/xe_tlb_inval.c
index 014a78502fe5..daabc9370510 100644
--- a/drivers/gpu/drm/xe/xe_tlb_inval.c
+++ b/drivers/gpu/drm/xe/xe_tlb_inval.c
@@ -44,11 +44,14 @@ static void xe_tlb_inval_fence_fini(struct xe_tlb_inval_fence *fence)
 static void
 xe_tlb_inval_fence_signal(struct xe_tlb_inval_fence *fence)
 {
+	struct xe_tlb_inval *tlb_inval = fence->tlb_inval;
 	bool stack = test_bit(FENCE_STACK_BIT, &fence->base.flags);
 
 	lockdep_assert_held(&fence->tlb_inval->pending_lock);
 
 	list_del(&fence->link);
+	if (list_empty(&tlb_inval->pending_fences))
+		cancel_delayed_work(&tlb_inval->fence_tdr);
 	trace_xe_tlb_inval_fence_signal(fence->tlb_inval->xe, fence);
 	xe_tlb_inval_fence_fini(fence);
 	dma_fence_signal(&fence->base);
@@ -464,3 +467,21 @@ void xe_tlb_inval_fence_init(struct xe_tlb_inval *tlb_inval,
 		dma_fence_get(&fence->base);
 	fence->tlb_inval = tlb_inval;
 }
+
+/**
+ * xe_tlb_inval_idle() - Initialize TLB invalidation is idle
+ * @tlb_inval: TLB invalidation client
+ *
+ * Check the TLB invalidation seqno to determine if it is idle (i.e., no TLB
+ * invalidations are in flight). Expected to be called in the backend after the
+ * fence has been added to the pending list, and takes this into account.
+ *
+ * Return: True if TLB invalidation client is idle, False otherwise
+ */
+bool xe_tlb_inval_idle(struct xe_tlb_inval *tlb_inval)
+{
+	lockdep_assert_held(&tlb_inval->seqno_lock);
+
+	guard(spinlock_irq)(&tlb_inval->pending_lock);
+	return list_is_singular(&tlb_inval->pending_fences);
+}
diff --git a/drivers/gpu/drm/xe/xe_tlb_inval.h b/drivers/gpu/drm/xe/xe_tlb_inval.h
index 858d0690f995..62089254fa23 100644
--- a/drivers/gpu/drm/xe/xe_tlb_inval.h
+++ b/drivers/gpu/drm/xe/xe_tlb_inval.h
@@ -43,4 +43,6 @@ xe_tlb_inval_fence_wait(struct xe_tlb_inval_fence *fence)
 
 void xe_tlb_inval_done_handler(struct xe_tlb_inval *tlb_inval, int seqno);
 
+bool xe_tlb_inval_idle(struct xe_tlb_inval *tlb_inval);
+
 #endif	/* _XE_TLB_INVAL_ */
-- 
2.34.1