pm, hello ??

pm, hello ??

[Giuliano Pochini]

I'm trying to add suspend/resume capability to the echoaudio driver. I wrote
susp/res functions, I attached them to struct pci_driver, I added
SNDRV_PCM_INFO_RESUME in struct snd_pcm_hardware.info, I added the two
cases in the trigger callback and the kernel has CONFIG_PM enabled. None of
the new code is called when I write in
/sys/devices/pci0001:10/0001:10:15.0/power/state . What am I missing ?

--
Giuliano.


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Re: pm, hello ??

[Takashi Iwai]

At Mon, 30 Jan 2006 22:55:11 +0100,
Giuliano Pochini wrote:
> 
> 
> I'm trying to add suspend/resume capability to the echoaudio driver. I wrote
> susp/res functions, I attached them to struct pci_driver, I added
> SNDRV_PCM_INFO_RESUME in struct snd_pcm_hardware.info, I added the two
> cases in the trigger callback and the kernel has CONFIG_PM enabled. None of
> the new code is called when I write in
> /sys/devices/pci0001:10/0001:10:15.0/power/state . What am I missing ?

No idea.  I bet something wrong in your kernel configuration or a
simple mistake like wrongly installed kernel image, etc.

BTW, SNDRV_PCM_INFO_RESUME should be added only if your driver really
supports the "full resume" mode.  i.e. the stream restarts at the very
same position where suspended.  Otherwise, dont' set that flag.  Still
the driver works as "partial resume".  Then the prepare is called
after resume to reset to a sane state.


Takashi


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Re: pm, hello ??

[Giuliano Pochini]

On Tue, 31 Jan 2006 15:06:35 +0100
Takashi Iwai <tiwai@suse.de> wrote:

> At Mon, 30 Jan 2006 22:55:11 +0100,
> Giuliano Pochini wrote:
> >
> > I'm trying to add suspend/resume capability to the echoaudio driver. I wrote
> > susp/res functions, I attached them to struct pci_driver, I added
> > SNDRV_PCM_INFO_RESUME in struct snd_pcm_hardware.info, I added the two
> > cases in the trigger callback and the kernel has CONFIG_PM enabled. None of
> > the new code is called when I write in
> > /sys/devices/pci0001:10/0001:10:15.0/power/state . What am I missing ?
>
> No idea.  I bet something wrong in your kernel configuration or a
> simple mistake like wrongly installed kernel image, etc.

Finally I found some time to debug it.

It happens that "echo 3 > file" actually writes "3\n" into the file.
lib/vsprintf.c:simple_strtoul() returns the first non-digit character in the
second argument. Then driver/base/power/sysfs.c:state_store() does:
	if (*rest)
		return -EINVAL;
*rest is always '\n', so it exits here.


> BTW, SNDRV_PCM_INFO_RESUME should be added only if your driver really
> supports the "full resume" mode.  i.e. the stream restarts at the very
> same position where suspended.  Otherwise, dont' set that flag.  Still
> the driver works as "partial resume".  Then the prepare is called
> after resume to reset to a sane state.

Nice to know. I can't resume the card exactly as it was before, indeed,
because the internal state of the DSP is unknown to the driver. I can only
restore all gains, monitors, etc., and restart transport from the last
period(s).


--
Giuliano.


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Re: pm, hello ??

[Lee Revell]

On Thu, 2006-02-09 at 23:12 +0100, Giuliano Pochini wrote:
> Finally I found some time to debug it.
> 
> It happens that "echo 3 > file" actually writes "3\n" into the file.
> lib/vsprintf.c:simple_strtoul() returns the first non-digit character
> in the
> second argument. Then driver/base/power/sysfs.c:state_store() does:
>         if (*rest)
>                 return -EINVAL;
> *rest is always '\n', so it exits here. 

There was a discussion not long ago on LKML about whether sysfs should
strip the trailing newline.  The consensus was that this is bloat, and
echo -n should be used.  I'm not sure I agree...

Lee



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