RE: [PATCH v3] mei: vsc: Don't stop/restart mei device during system suspend/resume

[Winkler, Tomas]

> -----Original Message-----
> From: Wu, Wentong <wentong.wu@xxxxxxxxx>
> Sent: Monday, May 27, 2024 3:39 PM
> To: sakari.ailus@xxxxxxxxxxxxxxx; Winkler, Tomas
> <tomas.winkler@xxxxxxxxx>; gregkh@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Wu, Wentong <wentong.wu@xxxxxxxxx>;
> stable@xxxxxxxxxxxxxxx; Yao, Hao <hao.yao@xxxxxxxxx>; Chen, Jason Z
> <jason.z.chen@xxxxxxxxx>
> Subject: [PATCH v3] mei: vsc: Don't stop/restart mei device during system
> suspend/resume
> 
> The dynamically created mei client device (mei csi) is used as one V4L2 sub
> device of the whole video pipeline, and the V4L2 connection graph is built by
> software node. The mei_stop() and mei_restart() will delete the old mei csi
> 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.
> 
> Removing mei_stop()/mei_restart() during system suspend/resume can fix
> the issue above and won't impact hardware actual power saving logic.
> 
> Fixes: f6085a96c973 ("mei: vsc: Unregister interrupt handler for system
> suspend")
> Cc: stable@xxxxxxxxxxxxxxx # for 6.8+
> Reported-by: Hao Yao <hao.yao@xxxxxxxxx>
> Signed-off-by: Wentong Wu <wentong.wu@xxxxxxxxx>
> Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Tested-by: Jason Chen <jason.z.chen@xxxxxxxxx>
> Tested-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Acked-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
> 
> ---
> Changes since v2:
>  - add change log which is not covered by v2, and no code change
> 
> Changes since v1:
>  - correct Fixes commit id in commit message, and no code change
> 
> ---
vX descriptions should go here 


>  drivers/misc/mei/platform-vsc.c | 39 +++++++++++++--------------------
>  1 file changed, 15 insertions(+), 24 deletions(-)
> 
> 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)
> 
>  static int mei_vsc_suspend(struct device *dev)  {
> -	struct mei_device *mei_dev = dev_get_drvdata(dev);
> -	struct mei_vsc_hw *hw = mei_dev_to_vsc_hw(mei_dev);
> +	struct mei_device *mei_dev;
> +	int ret = 0;
> 
> -	mei_stop(mei_dev);
> +	mei_dev = dev_get_drvdata(dev);
> +	if (!mei_dev)
> +		return -ENODEV;
> 
> -	mei_disable_interrupts(mei_dev);
> +	mutex_lock(&mei_dev->device_lock);
> 
> -	vsc_tp_free_irq(hw->tp);
> +	if (!mei_write_is_idle(mei_dev))
> +		ret = -EAGAIN;
> 
> -	return 0;
> +	mutex_unlock(&mei_dev->device_lock);
> +
> +	return ret;
>  }
> 
>  static int mei_vsc_resume(struct device *dev)  {
> -	struct mei_device *mei_dev = dev_get_drvdata(dev);
> -	struct mei_vsc_hw *hw = mei_dev_to_vsc_hw(mei_dev);
> -	int ret;
> -
> -	ret = vsc_tp_request_irq(hw->tp);
> -	if (ret)
> -		return ret;
> -
> -	ret = mei_restart(mei_dev);
> -	if (ret)
> -		goto err_free;
> +	struct mei_device *mei_dev;
> 
> -	/* start timer if stopped in suspend */
> -	schedule_delayed_work(&mei_dev->timer_work, HZ);
> +	mei_dev = dev_get_drvdata(dev);
> +	if (!mei_dev)
> +		return -ENODEV;
> 
>  	return 0;
> -
> -err_free:
> -	vsc_tp_free_irq(hw->tp);
> -
> -	return ret;
>  }
> 
>  static DEFINE_SIMPLE_DEV_PM_OPS(mei_vsc_pm_ops, mei_vsc_suspend,
> mei_vsc_resume);
> --
> 2.34.1