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

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Message-ID: <MW5PR11MB5787B1488ECC68EB6A5F44F08DF42@MW5PR11MB5787.namprd11.prod.outlook.com>
Date: Thu, 23 May 2024 13:02:13 +0000
From: "Wu, Wentong" <wentong.wu@...el.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
CC: "Winkler, Tomas" <tomas.winkler@...el.com>, "gregkh@...uxfoundation.org"
	<gregkh@...uxfoundation.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Yao, Hao" <hao.yao@...el.com>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>, "Chen, Jason Z"
	<jason.z.chen@...el.com>
Subject: RE: [PATCH] mei: vsc: Don't stop/restart mei device during system
 suspend/resume

> From: Sakari Ailus <sakari.ailus@...ux.intel.com>
> 
> Hi Wentong,
> 
> Thanks for the patch. I thought something like this would indeed have been
> possible.

Hi Sakari,

Thanks for your review.

> 
> On Thu, May 16, 2024 at 09:54:00AM +0800, Wentong Wu wrote:
> > 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: 386a766c4169 ("mei: Add MEI hardware support for IVSC device")
> 
> I think this should be instead:
> 
> Fixes: f6085a96c973 ("mei: vsc: Unregister interrupt handler for system
> suspend")
> 
> As this fix depends on the previous not-quite-as-good fix.

Agree, v2 patch will address this. Thanks

BR,
Wentong
> 
> Reviewed-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Tested-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> 
> > Cc: stable@...r.kernel.org # for 6.8+
> > Reported-by: Hao Yao <hao.yao@...el.com>
> > Signed-off-by: Wentong Wu <wentong.wu@...el.com>
> > Tested-by: Jason Chen <jason.z.chen@...el.com>
> > ---
> >  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);
> 
> --
> Kind regards,
> 
> Sakari Ailus