linux-kernel - Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card is inserted]

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Message-ID: <20080301151155.55209ebb@mjolnir.drzeus.cx>
Date:	Sat, 1 Mar 2008 15:11:55 +0100
From:	Pierre Ossman <drzeus-mmc@...eus.cx>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>,
	David Brownell <david-b@...bell.net>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card
 is inserted]

On Mon, 25 Feb 2008 15:00:51 -0500 (EST)
Alan Stern <stern@...land.harvard.edu> wrote:

> 
> Maybe a better approach would be to leave the workqueue unfreezable,
> and keep cancel_delayed_work_sync() in mmc_suspend_host().  It would
> then be necessary to add a test to verify, if there is a card attached,
> that the card is indeed suspended.  After all, it's possible that the
> cancel_delayed_work_sync() ended up waiting for a job already running
> on the workqueue to register a new card!  (The same would be true even 
> with flush_scheduled_work.)

How would that be handled? I'd prefer a patch as I'm evidently not up to date with how to fondle the pm stuff properly. :)

> 
> Also, as a bit of defensive programming, it might be a good idea to add
> a "suspended" flag to the mmc_host structure.  If mmc_rescan() sees
> that the flag is set then it should return immediately.  This would
> protect against host drivers that aren't careful to disable detect
> IRQs before calling mmc_suspend_host().

Indeed. I'll add that to my todo.

Rgds

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org
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