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

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Message-ID: <20251203040935.2685490-2-xulin.sun@windriver.com>
Date: Wed,  3 Dec 2025 12:09:33 +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,
        xulin.sun@...driver.com
Subject: [PATCH 1/3] media: wave5: Fix PM runtime usage count underflow

Symptom:
  ------------[ 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!

Root cause:
  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, causing
  the underflow warning.

Fix:
  Replace pm_runtime_put_sync() with pm_runtime_dont_use_autosuspend()
  which properly pairs with pm_runtime_use_autosuspend() from probe.
  This allows pm_runtime_disable() to handle reference count cleanup
  correctly regardless of current suspend state. The disable function
  internally handles the usage count properly without causing underflow.

Signed-off-by: Xulin Sun <xulin.sun@...driver.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