linux-kernel - [PATCH v2 1/3] media: wave5: Fix PM runtime usage count underflow

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Message-Id: <20251204094153.1530331-2-xulin.sun@windriver.com>
Date: Thu,  4 Dec 2025 17:41:51 +0800
From: Xulin Sun <xulin.sun@...driver.com>
To: nas.chung@...psnmedia.com, jackson.lee@...psnmedia.com, mchehab@...nel.org
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        nicolas.dufresne@...labora.com, hverkuil@...nel.org,
        dafna.hirschfeld@...labora.com, xulin.sun@...driver.com
Subject: [PATCH v2 1/3] media: wave5: Fix PM runtime usage count underflow

Replace pm_runtime_put_sync() with pm_runtime_dont_use_autosuspend() in
the remove path to properly pair with pm_runtime_use_autosuspend() from
probe. This allows pm_runtime_disable() to handle reference count cleanup
correctly regardless of current suspend state.

The driver calls pm_runtime_put_sync() unconditionally in remove, but the
device may already be suspended due to autosuspend configured in probe.
When autosuspend has already suspended the device, the usage count is 0,
and pm_runtime_put_sync() decrements it to -1.

This causes the following warning on module unload:

  ------------[ cut here ]------------
  WARNING: CPU: 1 PID: 963 at kernel/kthread.c:1430
    kthread_destroy_worker+0x84/0x98
  ...
  vdec 30210000.video-codec: Runtime PM usage count underflow!

Fixes: 9707a6254a8a ("media: chips-media: wave5: Add the v4l2 layer")
Signed-off-by: Xulin Sun <xulin.sun@...driver.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
---
 drivers/media/platform/chips-media/wave5/wave5-vpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu.c b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
index e1715d3f43b0..23aa3ab51a0e 100644
--- a/drivers/media/platform/chips-media/wave5/wave5-vpu.c
+++ b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
@@ -356,7 +356,7 @@ static void wave5_vpu_remove(struct platform_device *pdev)
 		hrtimer_cancel(&dev->hrtimer);
 	}
 
-	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
 	mutex_destroy(&dev->dev_lock);
-- 
2.49.1