[alsa-devel] [PATCH] ALSA: fm801: PCI core handles power state for us

[Takashi Iwai]

At Wed, 7 Jan 2015 12:35:10 +0200,
Andy Shevchenko wrote:
> 
> On Wed, Jan 7, 2015 at 8:54 AM, Takashi Iwai <tiwai at suse.de> wrote:
> > At Tue,  6 Jan 2015 22:39:15 +0200,
> > Andy Shevchenko wrote:
> >>
> >> There is no need to duplicate the work that is already done in the PCI
> >> driver core. The patch removes excerpts from suspend and resume
> >> callbacks.
> >>
> >> While here amend a definition of the snd_fm801_pm. The PM core has the
> >> stubs for non-PM_SLEEP cases, thus we can always define the variable.
> >
> > But this will result in a waste of bytes, no?  It's not a big deal,
> > but still...
> 
> We can leave it under #ifdef, the main purpose of the patch to remove
> duplicate PM work.

Yes.

> > above all, I couldn't find the code enabling/disabling pci device in
> > the default pci pm handlers.  pci_pm_default_resume_early() powers up
> > and restore the state.  These can be removed indeed.  But
> > pci_pm_restore() calls pci_pm_reenable_device() only as a fallback.
> > So it looks to me like the restore callback still needs to enable the
> > device explicitly.
> >
> > Am I missing anything obvious...?
> 
> The suspend_noirq is called at the end of the suspend process. It gets
> device to the lower power state. I think this was implemented by
> 46939f8b15e44f065d052e89ea4f2adc81fdc740.
> 
> There is a really nice documentation in dev_pm_ops description (linux/pm.h).

Well, this does only power up/down and register save/restore.  Where
pci_disable_device() and pci_enable_device() (or their variants) are
called in the framework?

> > In anyway, there are lots of similar codes in sound/pci/*, and I
> > prefer patching all them at once.  Of course the patches can be split
> > if it's better.
> 
> Better to do this driver-by-driver. But I don't care about other sound
> drivers right now.

And I do care :)  If applying this change, I'm going to put into a
series.  So please slim down to only the necessary part.


thanks,

Takashi

> 
> >
> >
> > thanks,
> >
> > Takashi
> >
> >> Signed-off-by: Andy Shevchenko <andy.shevchenko at gmail.com>
> >> ---
> >>  sound/pci/fm801.c | 22 ++--------------------
> >>  1 file changed, 2 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/sound/pci/fm801.c b/sound/pci/fm801.c
> >> index 9a2122f..dcda3c1 100644
> >> --- a/sound/pci/fm801.c
> >> +++ b/sound/pci/fm801.c
> >> @@ -1384,7 +1384,6 @@ static unsigned char saved_regs[] = {
> >>
> >>  static int snd_fm801_suspend(struct device *dev)
> >>  {
> >> -     struct pci_dev *pci = to_pci_dev(dev);
> >>       struct snd_card *card = dev_get_drvdata(dev);
> >>       struct fm801 *chip = card->private_data;
> >>       int i;
> >> @@ -1396,29 +1395,15 @@ static int snd_fm801_suspend(struct device *dev)
> >>       for (i = 0; i < ARRAY_SIZE(saved_regs); i++)
> >>               chip->saved_regs[i] = inw(chip->port + saved_regs[i]);
> >>       /* FIXME: tea575x suspend */
> >> -
> >> -     pci_disable_device(pci);
> >> -     pci_save_state(pci);
> >> -     pci_set_power_state(pci, PCI_D3hot);
> >>       return 0;
> >>  }
> >>
> >>  static int snd_fm801_resume(struct device *dev)
> >>  {
> >> -     struct pci_dev *pci = to_pci_dev(dev);
> >>       struct snd_card *card = dev_get_drvdata(dev);
> >>       struct fm801 *chip = card->private_data;
> >>       int i;
> >>
> >> -     pci_set_power_state(pci, PCI_D0);
> >> -     pci_restore_state(pci);
> >> -     if (pci_enable_device(pci) < 0) {
> >> -             dev_err(dev, "pci_enable_device failed, disabling device\n");
> >> -             snd_card_disconnect(card);
> >> -             return -EIO;
> >> -     }
> >> -     pci_set_master(pci);
> >> -
> >>       snd_fm801_chip_init(chip, 1);
> >>       snd_ac97_resume(chip->ac97);
> >>       snd_ac97_resume(chip->ac97_sec);
> >> @@ -1428,12 +1413,9 @@ static int snd_fm801_resume(struct device *dev)
> >>       snd_power_change_state(card, SNDRV_CTL_POWER_D0);
> >>       return 0;
> >>  }
> >> +#endif /* CONFIG_PM_SLEEP */
> >>
> >>  static SIMPLE_DEV_PM_OPS(snd_fm801_pm, snd_fm801_suspend, snd_fm801_resume);
> >> -#define SND_FM801_PM_OPS     &snd_fm801_pm
> >> -#else
> >> -#define SND_FM801_PM_OPS     NULL
> >> -#endif /* CONFIG_PM_SLEEP */
> >>
> >>  static struct pci_driver fm801_driver = {
> >>       .name = KBUILD_MODNAME,
> >> @@ -1441,7 +1423,7 @@ static struct pci_driver fm801_driver = {
> >>       .probe = snd_card_fm801_probe,
> >>       .remove = snd_card_fm801_remove,
> >>       .driver = {
> >> -             .pm = SND_FM801_PM_OPS,
> >> +             .pm = &snd_fm801_pm,
> >>       },
> >>  };
> >>
> >> --
> >> 1.8.3.101.g727a46b
> >>
> 
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
>