linux-kernel - [PATCH v2 2/4] drm/msm/adreno: fix runtime PM imbalance at gpu load

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Date:   Fri,  3 Mar 2023 17:48:05 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Bjorn Andersson <andersson@...nel.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v2 2/4] drm/msm/adreno: fix runtime PM imbalance at gpu load

A recent commit moved enabling of runtime PM to GPU load time (first
open()) but failed to update the error paths so that runtime PM is
disabled if initialisation of the GPU fails. This would trigger a
warning about the unbalanced disable count on the next open() attempt.

Note that pm_runtime_put_noidle() is sufficient to balance the usage
count when pm_runtime_put_sync() fails (and is chosen over
pm_runtime_resume_and_get() for consistency reasons).

Fixes: 4b18299b3365 ("drm/msm/adreno: Defer enabling runpm until hw_init()")
Cc: stable@...r.kernel.org      # 6.0
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 drivers/gpu/drm/msm/adreno/adreno_device.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
index c5c4c93b3689..f9a0b11c2e43 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_device.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
@@ -443,20 +443,21 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev)
 
 	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0) {
-		pm_runtime_put_sync(&pdev->dev);
+		pm_runtime_put_noidle(&pdev->dev);
 		DRM_DEV_ERROR(dev->dev, "Couldn't power up the GPU: %d\n", ret);
-		return NULL;
+		goto err_disable_rpm;
 	}
 
 	mutex_lock(&gpu->lock);
 	ret = msm_gpu_hw_init(gpu);
 	mutex_unlock(&gpu->lock);
-	pm_runtime_put_autosuspend(&pdev->dev);
 	if (ret) {
 		DRM_DEV_ERROR(dev->dev, "gpu hw init failed: %d\n", ret);
-		return NULL;
+		goto err_put_rpm;
 	}
 
+	pm_runtime_put_autosuspend(&pdev->dev);
+
 #ifdef CONFIG_DEBUG_FS
 	if (gpu->funcs->debugfs_init) {
 		gpu->funcs->debugfs_init(gpu, dev->primary);
@@ -465,6 +466,13 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev)
 #endif
 
 	return gpu;
+
+err_put_rpm:
+	pm_runtime_put_sync(&pdev->dev);
+err_disable_rpm:
+	pm_runtime_disable(&pdev->dev);
+
+	return NULL;
 }
 
 static int find_chipid(struct device *dev, struct adreno_rev *rev)
-- 
2.39.2