linux-kernel - [PATCH v2 3/7] drm/msm: Fix cx collapse issue during recovery

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Date:   Sat, 9 Jul 2022 11:29:31 +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>
CC:     Jonathan Marek <jonathan@...ek.ca>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Matthias Kaehlcke <mka@...omium.org>,
        "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>,
        "Dmitry Baryshkov" <dmitry.baryshkov@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Sean Paul <sean@...rly.run>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 3/7] 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 v1)

 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 16 ++++++++++++++--
 drivers/gpu/drm/msm/msm_gpu.c         |  2 --
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 4d50110..7ed347c 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1278,8 +1278,20 @@ 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);
+	/*
+	 * Now drop all the pm_runtime usage count to allow cx gdsc to collapse.
+	 * First drop the usage count from all active submits
+	 */
+	for (i = gpu->active_submits; i > 0; i--)
+		pm_runtime_put(&gpu->pdev->dev);
+
+	/* And the final one from recover worker */
+	pm_runtime_put_sync(&gpu->pdev->dev);
+
+	for (i = gpu->active_submits; i > 0; i--)
+		pm_runtime_get(&gpu->pdev->dev);
+
+	pm_runtime_get_sync(&gpu->pdev->dev);
 
 	msm_gpu_hw_init(gpu);
 }
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 18c1544..aa6f34f 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -422,9 +422,7 @@ 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
-- 
2.7.4