netdev - [PATCH 3/3] drm/nouveau: Add helper to check base fence

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Message-ID: <20250410092418.135258-5-phasta@kernel.org>
Date: Thu, 10 Apr 2025 11:24:19 +0200
From: Philipp Stanner <phasta@...nel.org>
To: Lyude Paul <lyude@...hat.com>,
	Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Sabrina Dubroca <sd@...asysnail.net>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Christian König <christian.koenig@....com>
Cc: dri-devel@...ts.freedesktop.org,
	nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-media@...r.kernel.org,
	linaro-mm-sig@...ts.linaro.org,
	Philipp Stanner <phasta@...nel.org>
Subject: [PATCH 3/3] drm/nouveau: Add helper to check base fence

Nouveau, unfortunately, checks whether a dma_fence is already siganled
at various different places with, at times, different methods. In
nouveau_fence_update() it generally signals all fences the hardware is
done with by evaluating the sequence number. That mechanism then has no
way to tell the caller nouveau_fence_done() whether a particular fence
is actually signaled, which is why the internal bits of the dma_fence
get checked.

This can be made more readable by providing a new wrapper, which can
then later be helpful to solve an unrelated bug.

Add nouveau_fence_base_is_signaled().

Signed-off-by: Philipp Stanner <phasta@...nel.org>
---
 drivers/gpu/drm/nouveau/nouveau_fence.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index db6f4494405c..0d58a81b3402 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -256,6 +256,12 @@ nouveau_fence_emit(struct nouveau_fence *fence)
 	return ret;
 }
 
+static inline bool
+nouveau_fence_base_is_signaled(struct nouveau_fence *fence)
+{
+	return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags);
+}
+
 bool
 nouveau_fence_done(struct nouveau_fence *fence)
 {
@@ -263,7 +269,7 @@ nouveau_fence_done(struct nouveau_fence *fence)
 	struct nouveau_channel *chan;
 	unsigned long flags;
 
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
+	if (nouveau_fence_base_is_signaled(fence))
 		return true;
 
 	spin_lock_irqsave(&fctx->lock, flags);
@@ -272,7 +278,7 @@ nouveau_fence_done(struct nouveau_fence *fence)
 		nvif_event_block(&fctx->event);
 	spin_unlock_irqrestore(&fctx->lock, flags);
 
-	return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags);
+	return nouveau_fence_base_is_signaled(fence);
 }
 
 static long
-- 
2.48.1