linux-kernel - Re: [linux-pm] Recent "Run the driver callback directly" patch breaks libertas suspend

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Date:	Sun, 25 Mar 2012 23:10:40 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	NeilBrown <neilb@...e.de>, linux-pm@...ts.linux-foundation.org,
	Chris Ball <cjb@...top.org>, linux-mmc@...r.kernel.org,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [linux-pm] Recent "Run the driver callback directly" patch breaks libertas suspend

On Sunday, March 25, 2012, Alan Stern wrote:
> On Sun, 25 Mar 2012, NeilBrown wrote:
> 
> > Hi Rafael,
> > 
> >  Your recent patch:
> >    commit 35cd133c
> >    PM: Run the driver callback directly if the subsystem one is not there
> > 
> >  breaks suspend for my libertas wifi and probably other SDIO devices.
> > 
> >  SDIO (and possible MMC in general) has a protocol where the suspend
> >  method can return -ENOSYS and this means "There is no point in suspending,
> >  just turn me off".
> > 
> >  The device itself "mmc1:0001" (I think) doesn't have any bus etc 'suspend'
> >  function so the new code call the device's suspend function which returns
> >  ENOSYS and the suspend fails.
> > 
> >  The previous code ignores the device as there is no bus suspend, and when it
> >  gets to suspend the ancestor - which for me is omap_hsmmc.1, it calls the
> >  device suspend function catches the ENOSYS, and turns it off.
> > 
> >  I suspect just reverting it isn't the right long term solution, however I
> >  can confirm that it works for me for now.
> > 
> >  I'm happy to try any alternate fixes you would like to suggest (but I cannot
> >  promise how quickly I will get the testing done).
> 
> With a little restructuring, this might be a good application for
> pm_runtime_no_callbacks().

That won't cover system suspend, though.

Thanks,
Rafael
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