need to get the interface cycled with autopm_get/_put() to let a device sleep

need to get the interface cycled with autopm_get/_put() to let a device sleep

[Oliver Neukum]

Hi,

I found a problem with the close() function of usbhid.
It fails to properly suspend device that don't support
remote wake-up. The power core does not retry an autosuspend
that failed due to a lack of support for remote wake-up.

So there needs to be a _put() if the need for remote wake-up
is rescinded. The current state of affairs leads to joysticks
never going to sleep again after use.

But I am not happy with the simple solution. It needlessly
wakes up suspended devices. So, I tried using
usb_autopm_get_interface_no_resume(). To my considerable
surprise that didn't work. I cannot understand why.

So what is to be done?

	Regards
		Oliver


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Re: need to get the interface cycled with autopm_get/_put() to let a device sleep

[Alan Stern]

On Wed, 15 Apr 2015, Oliver Neukum wrote:

> Hi,
> 
> I found a problem with the close() function of usbhid.
> It fails to properly suspend device that don't support
> remote wake-up. The power core does not retry an autosuspend
> that failed due to a lack of support for remote wake-up.
> 
> So there needs to be a _put() if the need for remote wake-up
> is rescinded. The current state of affairs leads to joysticks
> never going to sleep again after use.
> 
> But I am not happy with the simple solution. It needlessly
> wakes up suspended devices. So, I tried using
> usb_autopm_get_interface_no_resume(). To my considerable
> surprise that didn't work. I cannot understand why.

In what way did it not work?

> So what is to be done?

Start with a little debugging.  When you do the put, what happens 
inside autosuspend_check()?

Alan Stern