linux-kernel - Re: [PATCH v4 2/4] media: imx-jpeg: Use devm_pm_runtime

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Message-ID: <0f2cc5d0-9abe-47c6-abdc-42ebe5fb5b35@oss.nxp.com>
Date: Wed, 4 Feb 2026 09:36:06 +0800
From: "Ming Qian(OSS)" <ming.qian@....nxp.com>
To: Frank Li <Frank.li@....com>
Cc: mchehab@...nel.org, hverkuil-cisco@...all.nl, mirela.rabulea@....nxp.com,
 nicolas@...fresne.ca, shawnguo@...nel.org, s.hauer@...gutronix.de,
 kernel@...gutronix.de, festevam@...il.com, xiahong.bao@....com,
 eagle.zhou@....com, linux-imx@....com, imx@...ts.linux.dev,
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 2/4] media: imx-jpeg: Use devm_pm_runtime_enable()
 helper

Hi Frank,

On 2/4/2026 12:56 AM, Frank Li wrote:
> On Tue, Feb 03, 2026 at 04:23:39PM +0800, ming.qian@....nxp.com wrote:
>> From: Ming Qian <ming.qian@....nxp.com>
>>
>> Use devm_pm_runtime_enable() to simplify probe and exit paths.
>>
>> No functional change.
>>
>> Signed-off-by: Ming Qian <ming.qian@....nxp.com>
>> ---
>>   drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c | 15 ++++++++++++---
>>   1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
>> index 39022c1bf36d..877e6c4f7406 100644
>> --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
>> +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
>> @@ -2971,12 +2971,22 @@ static int mxc_jpeg_probe(struct platform_device *pdev)
>>   			  jpeg->dec_vdev->minor);
>>
>>   	platform_set_drvdata(pdev, jpeg);
>> -	pm_runtime_enable(dev);
>> +	ret = devm_pm_runtime_enable(dev);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to enable runtime PM: %d\n", ret);
>> +		goto err_pm;
>> +	}
>>
>>   	return 0;
>>
>> +err_pm:
>> +	video_unregister_device(jpeg->dec_vdev);
>> +	/* set NULL to prevent double-free */
>> +	jpeg->dec_vdev = NULL;
> 
> code have not simplied, you add addtional goto label. You can use
> devm_add_action_or_reset().
> 
> Frank
> 

I don't quite understand the difference compared to directly using
devm_pm_runtime_enable.

int devm_pm_runtime_enable(struct device *dev)
{
	pm_runtime_enable(dev);

	return devm_add_action_or_reset(dev, pm_runtime_disable_action, dev);
}

We still need to check the return value of devm_add_action_or_reset and
perform the corresponding error handling.
We may still add the goto label.

Regards,
Ming

>>   err_vdev_register:
>> -	video_device_release(jpeg->dec_vdev);
>> +	/* Only release if allocation succeeded but registration failed */
>> +	if (jpeg->dec_vdev)
>> +		video_device_release(jpeg->dec_vdev);
>>
>>   err_vdev_alloc:
>>   	v4l2_m2m_release(jpeg->m2m_dev);
>> @@ -3047,7 +3057,6 @@ static void mxc_jpeg_remove(struct platform_device *pdev)
>>
>>   	mxc_jpeg_free_slot_data(jpeg);
>>
>> -	pm_runtime_disable(&pdev->dev);
>>   	video_unregister_device(jpeg->dec_vdev);
>>   	v4l2_m2m_release(jpeg->m2m_dev);
>>   	v4l2_device_unregister(&jpeg->v4l2_dev);
>> --
>> 2.52.0
>>