linux-kernel - [PATCH v2 1/2] drm/msm/gpu: Wait for idle before suspending

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Date:   Sat,  8 Jan 2022 09:42:46 -0800
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Jonathan Marek <jonathan@...ek.ca>,
        Vladimir Lypak <vladimir.lypak@...il.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 1/2] drm/msm/gpu: Wait for idle before suspending

From: Rob Clark <robdclark@...omium.org>

System suspend uses pm_runtime_force_suspend(), which cheekily bypasses
the runpm reference counts.  This doesn't actually work so well when the
GPU is active.  So add a reasonable delay waiting for the GPU to become
idle.

Alternatively we could just return -EBUSY in this case, but that has the
disadvantage of causing system suspend to fail.

Signed-off-by: Rob Clark <robdclark@...omium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/gpu/drm/msm/adreno/adreno_device.c | 18 ++++++++++++++++++
 drivers/gpu/drm/msm/msm_gpu.c              |  3 +++
 drivers/gpu/drm/msm/msm_gpu.h              |  3 +++
 3 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
index 93005839b5da..a502ffafb739 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_device.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
@@ -608,9 +608,27 @@ static int adreno_resume(struct device *dev)
 	return gpu->funcs->pm_resume(gpu);
 }
 
+static int active_submits(struct msm_gpu *gpu)
+{
+	int active_submits;
+	mutex_lock(&gpu->active_lock);
+	active_submits = gpu->active_submits;
+	mutex_unlock(&gpu->active_lock);
+	return active_submits;
+}
+
 static int adreno_suspend(struct device *dev)
 {
 	struct msm_gpu *gpu = dev_to_gpu(dev);
+	int remaining;
+
+	remaining = wait_event_timeout(gpu->retire_event,
+				       active_submits(gpu) > 0,
+				       msecs_to_jiffies(1000));
+	if (remaining == 0) {
+		dev_err(dev, "Timeout waiting for GPU to suspend\n");
+		return -EBUSY;
+	}
 
 	return gpu->funcs->pm_suspend(gpu);
 }
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 0f78c2615272..2c1049c0ea14 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -703,6 +703,8 @@ static void retire_submits(struct msm_gpu *gpu)
 			}
 		}
 	}
+
+	wake_up_all(&gpu->retire_event);
 }
 
 static void retire_worker(struct kthread_work *work)
@@ -848,6 +850,7 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
 	INIT_LIST_HEAD(&gpu->active_list);
 	mutex_init(&gpu->active_lock);
 	mutex_init(&gpu->lock);
+	init_waitqueue_head(&gpu->retire_event);
 	kthread_init_work(&gpu->retire_work, retire_worker);
 	kthread_init_work(&gpu->recover_work, recover_worker);
 	kthread_init_work(&gpu->fault_work, fault_worker);
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 445c6bfd4b6b..92aa1e9196c6 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -230,6 +230,9 @@ struct msm_gpu {
 	/* work for handling GPU recovery: */
 	struct kthread_work recover_work;
 
+	/** retire_event: notified when submits are retired: */
+	wait_queue_head_t retire_event;
+
 	/* work for handling active-list retiring: */
 	struct kthread_work retire_work;
 
-- 
2.33.1