[Xen-devel] Re: [RFC PATCH] set current_state to D0 in register_slot

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 4 Mar 2011, Jesse Barnes wrote:
> On Mon, 28 Feb 2011 16:20:11 +0000
> Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> 
> > Hi all,
> > if a device doesn't support power management (pm_cap == 0) but it is
> > acpi_pci_power_manageable() because there is a _PS0 method declared for
> > it and _EJ0 is also declared for the slot then nobody is going to set
> > current_state = PCI_D0 for this device.  This is what I think it is
> > happening:
> > 
> > 
> > pci_enable_device
> >     |
> > __pci_enable_device_flags
> > /* here we do not set current_state because !pm_cap */
> >     |
> > do_pci_enable_device
> >     |
> > pci_set_power_state
> >     |
> > __pci_start_power_transition
> >     |
> > pci_platform_power_transition
> > /* platform_pci_power_manageable() calls acpi_pci_power_manageable that
> >  * returns true */
> >     |
> > platform_pci_set_power_state
> > /* acpi_pci_set_power_state gets called and does nothing because the
> >  * acpi device has _EJ0, see the comment "If the ACPI device has _EJ0,
> >  * ignore the device" */
> > 
> > 
> > at this point if we refer to the commit message that introduced the
> > comment above (10b3dcae0f275e2546e55303d64ddbb58cec7599), it is up to
> > the hotplug driver to set the state to D0.
> > However AFAICT the pci hotplug driver never does, in fact
> > drivers/pci/hotplug/acpiphp_glue.c:register_slot sets the slot flags to
> > (SLOT_ENABLED | SLOT_POWEREDON) but it does not set the pci device
> > current state to PCI_D0.
> > 
> > So my proposed fix is also to set current_state = PCI_D0 in
> > register_slot.
> > Comments are very welcome.
> > 
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> Yeah, looks fine.  ACPIPHP is happy for the attention. :)

Great, thanks!
Would you be OK with taking this patch in your tree?
Or do you prefer me to send to it Linus myself?

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