linux-kernel - [PATCH v5 4/7] drm/msm: Fix cx collapse issue during recovery

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Message-ID: <20220819015030.v5.4.I4ac27a0b34ea796ce0f938bb509e257516bc6f57@changeid>
Date:   Fri, 19 Aug 2022 01:52:12 +0530
From:   Akhil P Oommen <quic_akhilpo@...cinc.com>
To:     freedreno <freedreno@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        Rob Clark <robdclark@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        "Dmitry Baryshkov" <dmitry.baryshkov@...aro.org>
CC:     Jordan Crouse <jordan@...micpenguin.net>,
        Matthias Kaehlcke <mka@...omium.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        Douglas Anderson <dianders@...omium.org>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        "Abhinav Kumar" <quic_abhinavk@...cinc.com>,
        Chia-I Wu <olvaffe@...il.com>,
        "Daniel Vetter" <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Sean Paul <sean@...rly.run>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 4/7] drm/msm: Fix cx collapse issue during recovery

There are some hardware logic under CX domain. For a successful
recovery, we should ensure cx headswitch collapses to ensure all the
stale states are cleard out. This is especially true to for a6xx family
where we can GMU co-processor.

Currently, cx doesn't collapse due to a devlink between gpu and its
smmu. So the *struct gpu device* needs to be runtime suspended to ensure
that the iommu driver removes its vote on cx gdsc.

Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
---

(no changes since v4)

Changes in v4:
- Keep active_submit lock across the suspend & resume (Rob)
- Clear gpu->active_submits to silence a WARN() during runpm suspend (Rob)

Changes in v3:
- Simplied the pm refcount drop since we have just a single refcount now
for all active submits

 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 32 +++++++++++++++++++++++++++++---
 drivers/gpu/drm/msm/msm_gpu.c         |  4 +---
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 42ed9a3..0c8f19e 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1193,7 +1193,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
-	int i;
+	int i, active_submits;
 
 	adreno_dump_info(gpu);
 
@@ -1210,8 +1210,34 @@ static void a6xx_recover(struct msm_gpu *gpu)
 	 */
 	gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_GMU_PWR_COL_KEEPALIVE, 0);
 
-	gpu->funcs->pm_suspend(gpu);
-	gpu->funcs->pm_resume(gpu);
+	pm_runtime_dont_use_autosuspend(&gpu->pdev->dev);
+
+	/* active_submit won't change until we make a submission */
+	mutex_lock(&gpu->active_lock);
+	active_submits = gpu->active_submits;
+
+	/*
+	 * Temporarily clear active_submits count to silence a WARN() in the
+	 * runtime suspend cb
+	 */
+	gpu->active_submits = 0;
+
+	/* Drop the rpm refcount from active submits */
+	if (active_submits)
+		pm_runtime_put(&gpu->pdev->dev);
+
+	/* And the final one from recover worker */
+	pm_runtime_put_sync(&gpu->pdev->dev);
+
+	pm_runtime_use_autosuspend(&gpu->pdev->dev);
+
+	if (active_submits)
+		pm_runtime_get(&gpu->pdev->dev);
+
+	pm_runtime_get_sync(&gpu->pdev->dev);
+
+	gpu->active_submits = active_submits;
+	mutex_unlock(&gpu->active_lock);
 
 	msm_gpu_hw_init(gpu);
 }
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 1945efb..07e55a6 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -426,9 +426,7 @@ static void recover_worker(struct kthread_work *work)
 		/* retire completed submits, plus the one that hung: */
 		retire_submits(gpu);
 
-		pm_runtime_get_sync(&gpu->pdev->dev);
 		gpu->funcs->recover(gpu);
-		pm_runtime_put_sync(&gpu->pdev->dev);
 
 		/*
 		 * Replay all remaining submits starting with highest priority
@@ -445,7 +443,7 @@ static void recover_worker(struct kthread_work *work)
 		}
 	}
 
-	pm_runtime_put_sync(&gpu->pdev->dev);
+	pm_runtime_put(&gpu->pdev->dev);
 
 	mutex_unlock(&gpu->lock);
 
-- 
2.7.4