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Subject[PATCH 2/2] drm/msm: Signal fences sooner
Date
From: Rob Clark <robdclark@chromium.org>

Nothing we do to in update_fences() can't be done in an atomic context,
so move this into the GPU's irq context to reduce latency (and call
dma_fence_signal() so we aren't relying on dma_fence_is_signaled() which
would defeat the purpose).

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/gpu/drm/msm/msm_gpu.c | 44 +++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 0ebf7bc6ad09..647af45cf892 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -278,16 +278,18 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
uint32_t fence)
{
struct msm_gem_submit *submit;
+ unsigned long flags;

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
list_for_each_entry(submit, &ring->submits, node) {
if (submit->seqno > fence)
break;

msm_update_fence(submit->ring->fctx,
submit->fence->seqno);
+ dma_fence_signal(submit->fence);
}
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);
}

#ifdef CONFIG_DEV_COREDUMP
@@ -443,15 +445,16 @@ static struct msm_gem_submit *
find_submit(struct msm_ringbuffer *ring, uint32_t fence)
{
struct msm_gem_submit *submit;
+ unsigned long flags;

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
list_for_each_entry(submit, &ring->submits, node) {
if (submit->seqno == fence) {
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);
return submit;
}
}
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);

return NULL;
}
@@ -547,11 +550,12 @@ static void recover_worker(struct kthread_work *work)
*/
for (i = 0; i < gpu->nr_rings; i++) {
struct msm_ringbuffer *ring = gpu->rb[i];
+ unsigned long flags;

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
list_for_each_entry(submit, &ring->submits, node)
gpu->funcs->submit(gpu, submit);
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);
}
}

@@ -641,7 +645,7 @@ static void hangcheck_handler(struct timer_list *t)
hangcheck_timer_reset(gpu);

/* workaround for missing irq: */
- kthread_queue_work(gpu->worker, &gpu->retire_work);
+ msm_gpu_retire(gpu);
}

/*
@@ -752,6 +756,7 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
int index = submit->seqno % MSM_GPU_SUBMIT_STATS_COUNT;
volatile struct msm_gpu_submit_stats *stats;
u64 elapsed, clock = 0;
+ unsigned long flags;
int i;

stats = &ring->memptrs->stats[index];
@@ -781,9 +786,9 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
pm_runtime_mark_last_busy(&gpu->pdev->dev);
pm_runtime_put_autosuspend(&gpu->pdev->dev);

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
list_del(&submit->node);
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);

msm_gem_submit_put(submit);
}
@@ -798,11 +803,12 @@ static void retire_submits(struct msm_gpu *gpu)

while (true) {
struct msm_gem_submit *submit = NULL;
+ unsigned long flags;

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
submit = list_first_entry_or_null(&ring->submits,
struct msm_gem_submit, node);
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);

/*
* If no submit, we are done. If submit->fence hasn't
@@ -821,10 +827,6 @@ static void retire_submits(struct msm_gpu *gpu)
static void retire_worker(struct kthread_work *work)
{
struct msm_gpu *gpu = container_of(work, struct msm_gpu, retire_work);
- int i;
-
- for (i = 0; i < gpu->nr_rings; i++)
- update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);

retire_submits(gpu);
}
@@ -832,6 +834,11 @@ static void retire_worker(struct kthread_work *work)
/* call from irq handler to schedule work to retire bo's */
void msm_gpu_retire(struct msm_gpu *gpu)
{
+ int i;
+
+ for (i = 0; i < gpu->nr_rings; i++)
+ update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
+
kthread_queue_work(gpu->worker, &gpu->retire_work);
update_sw_cntrs(gpu);
}
@@ -842,6 +849,7 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
struct drm_device *dev = gpu->dev;
struct msm_drm_private *priv = dev->dev_private;
struct msm_ringbuffer *ring = submit->ring;
+ unsigned long flags;
int i;

WARN_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -879,9 +887,9 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
*/
msm_gem_submit_get(submit);

- spin_lock(&ring->submit_lock);
+ spin_lock_irqsave(&ring->submit_lock, flags);
list_add_tail(&submit->node, &ring->submits);
- spin_unlock(&ring->submit_lock);
+ spin_unlock_irqrestore(&ring->submit_lock, flags);

gpu->funcs->submit(gpu, submit);
priv->lastctx = submit->queue->ctx;
--
2.31.1
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