linux-kernel - Re: [PATCH 1/1] driver core: disable device's runtime pm during shutdown

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Date:	Mon, 14 Nov 2011 23:27:37 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Peter Chen <peter.chen@...escale.com>, gregkh@...e.de
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	stern@...land.harvard.edu, hzpeterchen@...il.com
Subject: Re: [PATCH 1/1] driver core: disable device's runtime pm during shutdown

On Monday, November 14, 2011, Peter Chen wrote:
> There may be an issue when the user issue "reboot/shutdown" command, then
> the device has shut down its hardware, after that, this runtime-pm featured
> device's driver will probably be scheduled to do its suspend routine,
> and at its suspend routine, it may access hardware, but the device has
> already shutdown physically, then the system hang may be occurred.
> 
> I ran out this issue using an auto-suspend supported USB devices, like
> 3G modem, keyboard. The usb runtime suspend routine may be scheduled
> after the usb controller has been shut down, and the usb runtime suspend
> routine will try to suspend its roothub(controller), it will access
> register, then the system hang occurs as the controller is shutdown.
> Signed-off-by: Peter Chen <peter.chen@...escale.com>

Greg, do you want me to take this one?

Rafael


> ---
>  drivers/base/core.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index bc8729d..78445f4 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -22,6 +22,7 @@
>  #include <linux/kallsyms.h>
>  #include <linux/mutex.h>
>  #include <linux/async.h>
> +#include <linux/pm_runtime.h>
>  
>  #include "base.h"
>  #include "power/power.h"
> @@ -1742,6 +1743,8 @@ void device_shutdown(void)
>  		 */
>  		list_del_init(&dev->kobj.entry);
>  		spin_unlock(&devices_kset->list_lock);
> +		/* Disable all device's runtime power management */
> +		pm_runtime_disable(dev);
>  
>  		if (dev->bus && dev->bus->shutdown) {
>  			dev_dbg(dev, "shutdown\n");
> 

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