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From: "Winkler, Tomas" <tomas.winkler@intel.com>
To: "Wu, Wentong" <wentong.wu@intel.com>, "sakari.ailus@linux.intel.com"
	<sakari.ailus@linux.intel.com>, "gregkh@linuxfoundation.org"
	<gregkh@linuxfoundation.org>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>, "Yao, Hao"
	<hao.yao@intel.com>, "Chen, Jason Z" <jason.z.chen@intel.com>
Subject: RE: [PATCH v3] mei: vsc: Don't stop/restart mei device during system
 suspend/resume
Thread-Topic: [PATCH v3] mei: vsc: Don't stop/restart mei device during system
 suspend/resume
Thread-Index: AQHasC/Q36BTTG7vREyPCcbfxlnlZbGrhpSg
Date: Mon, 27 May 2024 20:23:46 +0000
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References: <20240527123835.522384-1-wentong.wu@intel.com>
In-Reply-To: <20240527123835.522384-1-wentong.wu@intel.com>
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> -----Original Message-----
> From: Wu, Wentong <wentong.wu@intel.com>
> Sent: Monday, May 27, 2024 3:39 PM
> To: sakari.ailus@linux.intel.com; Winkler, Tomas
> <tomas.winkler@intel.com>; gregkh@linuxfoundation.org
> Cc: linux-kernel@vger.kernel.org; Wu, Wentong <wentong.wu@intel.com>;
> stable@vger.kernel.org; Yao, Hao <hao.yao@intel.com>; Chen, Jason Z
> <jason.z.chen@intel.com>
> Subject: [PATCH v3] mei: vsc: Don't stop/restart mei device during system
> suspend/resume
>=20
> The dynamically created mei client device (mei csi) is used as one V4L2 s=
ub
> device of the whole video pipeline, and the V4L2 connection graph is buil=
t by
> software node. The mei_stop() and mei_restart() will delete the old mei c=
si
> client device and create a new mei client device, which will cause the
> software node information saved in old mei csi device lost and the whole
> video pipeline will be broken.
>=20
> Removing mei_stop()/mei_restart() during system suspend/resume can fix
> the issue above and won't impact hardware actual power saving logic.
>=20
> Fixes: f6085a96c973 ("mei: vsc: Unregister interrupt handler for system
> suspend")
> Cc: stable@vger.kernel.org # for 6.8+
> Reported-by: Hao Yao <hao.yao@intel.com>
> Signed-off-by: Wentong Wu <wentong.wu@intel.com>
> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Tested-by: Jason Chen <jason.z.chen@intel.com>
> Tested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
>=20
> ---
> Changes since v2:
>  - add change log which is not covered by v2, and no code change
>=20
> Changes since v1:
>  - correct Fixes commit id in commit message, and no code change
>=20
> ---
vX descriptions should go here=20


>  drivers/misc/mei/platform-vsc.c | 39 +++++++++++++--------------------
>  1 file changed, 15 insertions(+), 24 deletions(-)
>=20
> diff --git a/drivers/misc/mei/platform-vsc.c b/drivers/misc/mei/platform-
> vsc.c index b543e6b9f3cf..1ec65d87488a 100644
> --- a/drivers/misc/mei/platform-vsc.c
> +++ b/drivers/misc/mei/platform-vsc.c
> @@ -399,41 +399,32 @@ static void mei_vsc_remove(struct platform_device
> *pdev)
>=20
>  static int mei_vsc_suspend(struct device *dev)  {
> -	struct mei_device *mei_dev =3D dev_get_drvdata(dev);
> -	struct mei_vsc_hw *hw =3D mei_dev_to_vsc_hw(mei_dev);
> +	struct mei_device *mei_dev;
> +	int ret =3D 0;
>=20
> -	mei_stop(mei_dev);
> +	mei_dev =3D dev_get_drvdata(dev);
> +	if (!mei_dev)
> +		return -ENODEV;
>=20
> -	mei_disable_interrupts(mei_dev);
> +	mutex_lock(&mei_dev->device_lock);
>=20
> -	vsc_tp_free_irq(hw->tp);
> +	if (!mei_write_is_idle(mei_dev))
> +		ret =3D -EAGAIN;
>=20
> -	return 0;
> +	mutex_unlock(&mei_dev->device_lock);
> +
> +	return ret;
>  }
>=20
>  static int mei_vsc_resume(struct device *dev)  {
> -	struct mei_device *mei_dev =3D dev_get_drvdata(dev);
> -	struct mei_vsc_hw *hw =3D mei_dev_to_vsc_hw(mei_dev);
> -	int ret;
> -
> -	ret =3D vsc_tp_request_irq(hw->tp);
> -	if (ret)
> -		return ret;
> -
> -	ret =3D mei_restart(mei_dev);
> -	if (ret)
> -		goto err_free;
> +	struct mei_device *mei_dev;
>=20
> -	/* start timer if stopped in suspend */
> -	schedule_delayed_work(&mei_dev->timer_work, HZ);
> +	mei_dev =3D dev_get_drvdata(dev);
> +	if (!mei_dev)
> +		return -ENODEV;
>=20
>  	return 0;
> -
> -err_free:
> -	vsc_tp_free_irq(hw->tp);
> -
> -	return ret;
>  }
>=20
>  static DEFINE_SIMPLE_DEV_PM_OPS(mei_vsc_pm_ops, mei_vsc_suspend,
> mei_vsc_resume);
> --
> 2.34.1