linux-kernel - Re: [alsa-devel] PNP_DRIVER_RES_DISABLE breaks swsusp at least with snd

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Date:	Thu, 10 Jan 2008 08:58:28 +0100 (CET)
From:	Jaroslav Kysela <perex@...ex.cz>
To:	Rene Herman <rene.herman@...access.nl>
cc:	Ondrej Zary <linux@...nbow-software.org>,
	ALSA development <alsa-devel@...a-project.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bjorn.helgaas@...com>
Subject: Re: [alsa-devel] PNP_DRIVER_RES_DISABLE breaks swsusp at least with
 snd_cs4236

On Thu, 10 Jan 2008, Rene Herman wrote:

> On 09-01-08 23:43, Ondrej Zary wrote:
> 
> Jaroslav -- in your role as ISA-PnP maintainer and Bjorn, in yours as 
> having been foollish enough to touch PnP recently:
> 
> > as hibernation (swsusp) started to work with my CPU, I found that my Turtle 
> > Beach Malibu stops working after resume from hibernation. It's caused by fact 
> > that the card is not enabled on the pnp layer during resume - and thus card 
> > registers are inaccessible (reads return FFs, writes go nowhere).
> > 
> > During resume, pnp_bus_resume() in drivers/pnp/driver.c is called for each pnp 
> > device. This function calls pnp_start_dev() only when the 
> > PNP_DRIVER_RES_DO_NOT_CHANGE bit is NOT seting pnp_drv->flags. But the cs4236 
> > driver in sound/isa/cs423x/cs4236.c explicitly sets the .flags to 
> > PNP_DRIVER_RES_DISABLE - it's value is 3 and that includes 
> > PNP_DRIVER_RES_DO_NOT_CHANGE bit.
> 
> Ehm. Isn't that a bit unexpected:
> 
> #define PNP_DRIVER_RES_DO_NOT_CHANGE    0x0001  /* do not change the state 
> of the device */
> #define PNP_DRIVER_RES_DISABLE          0x0003  /* ensure the device is 
> disabled */
> 
> I'd say that disabling is changing, so isn't this just a braino where 
> someone meant to write 2 instead of 3?

It's irrelevant. I think that condition in driver.c in suspend and resume 
callbacks is invalid, because PNP_DRIVER_RES_DO_NOT_CHANGE means that 
resources should not be changed in the pnp core but only in the driver, 
but in suspend/resume process are resources preserved, so the condition 
should be removed.

Author of this code is:

author Pierre Ossman <drzeus-list@...eus.cx> Tue, 29 Nov 2005 09:09:32 +0100
committer Jaroslav Kysela <perex@...e.cz> Tue, 03 Jan 2006 12:31:30 +0100

    [ALSA] [PATCH] alsa: Improved PnP suspend support

    Also use the PnP functions to start/stop the devices during the suspend so
    that drivers will not have to duplicate this code.

    Cc: Adam Belay <ambx1@....rr.com>
    Cc: Jaroslav Kysela <perex@...e.cz>
    Cc: Takashi Iwai <tiwai@...e.de>

    Signed-off-by: Pierre Ossman <drzeus@...eus.cx>
    Signed-off-by: Andrew Morton <akpm@...l.org>
    Signed-off-by: Takashi Iwai <tiwai@...e.de>


						Jaroslav

-----
Jaroslav Kysela <perex@...ex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.

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