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

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Message-ID: <Pine.LNX.4.44L0.1203251116290.16994-100000@netrider.rowland.org>
Date:	Sun, 25 Mar 2012 11:18:31 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	NeilBrown <neilb@...e.de>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	<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 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().

Alan Stern

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