On Wednesday, 7 of May 2008, Pavel Machek wrote:
> Hi!
>
> > From: Rafael J. Wysocki <rjw@xxxxxxx>
> >
> > The new suspend and hibernation callbacks introduced with
> > 'struct pm_ops' and 'struct pm_ext_ops' do not take a
> > pm_message_t argument, so the drivers using them will not be able
> > to use pci_choose_state() in its present form. For this reason,
> > introduce the new function pci_preferred_state() playing the role
> > of pci_choose_state(), but taking only a pointer to the device
> > object.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> > ---
> > drivers/pci/pci.c | 33 ++++++++++++++++++++++++++++++++-
> > include/linux/pci.h | 1 +
> > include/linux/pm.h | 10 ++++++++++
> > 3 files changed, 43 insertions(+), 1 deletion(-)
> >
> > Index: linux-2.6/drivers/pci/pci.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/pci/pci.c
> > +++ linux-2.6/drivers/pci/pci.c
> > @@ -509,7 +509,38 @@ pci_set_power_state(struct pci_dev *dev,
> > }
> >
> > pci_power_t (*platform_pci_choose_state)(struct pci_dev *dev);
> > -
> > +
> > +/**
> > + * pci_preferred_state - Choose the preferred power state of a PCI device
> > + * @dev: PCI device to be put into the low power state
> > + * @sp: Information aboutabout what the driver would prefer to do with
> > + * the device if there were no platform-implemeted policy.
> > + *
> > + * Returns PCI power state suitable for given device and given suspend policy.
> > + * The policy, however, is only used if platform_pci_choose_state() fails or is
> > + * not present. Otherwise, it is assumed that platform_pci_choose_state()
> > + * implements the right policy.
> > + */
> > +
> > +pci_power_t pci_preferred_state(struct pci_dev *dev, enum suspend_policy sp)
> > +{
> > + pci_power_t ret;
> > +
> > + if (!pci_find_capability(dev, PCI_CAP_ID_PM))
> > + return PCI_D0;
> > +
> > + ret = (sp == SP_TURN_OFF) ? PCI_D3hot : PCI_D0;
> > + if (platform_pci_choose_state) {
> > + pci_power_t platform_ret = platform_pci_choose_state(dev);
> > +
> > + if (platform_ret != PCI_POWER_ERROR)
> > + ret = platform_ret;
> > + }
> > + return ret;
> > +}
> > +
> > +EXPORT_SYMBOL(pci_preferred_state);
>
> I don't get it. How is driver supposed to use this? How does the
> driver decide between SP_TURN_OFF and SP_TURN_ON?
>
> ...and it seems to be clearer to just inline this in the driver... or
> pass PCI_D3hot/PCI_D0 to it, instead of inventing yet another
> define...
I thought about that too. I'd like to know what the other people think,
though.
Thanks,
Rafael
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