Andrew Morton <[EMAIL PROTECTED]> wrote:
>
> Shaohua Li <[EMAIL PROTECTED]> wrote:
> >
> > Hi,
> > Considering below scenario:
> > 1.Unload a PCI device's driver, the device ->current remains in PCI_D0.
> > 2.Do suspend/resume circle. After that, BIOS puts the device to D3.
> > 3.Reload the device driver. The calling pci_set_power_state in the
> > driver can't change the state to D0, as set_power_state thinks the
> > device is already in D0.
> > This patch assumes drivers call pci_disable_device at unloading and sets
> > device's state to unknown.
> > A bug is reported at http://bugzilla.kernel.org/show_bug.cgi?id=6024
> >
> > Signed-off-by: Shaohua Li <[EMAIL PROTECTED]>
> > ---
> >
> > linux-2.6.16-rc3-root/drivers/pci/pci.c | 1 +
> > 1 files changed, 1 insertion(+)
> >
> > diff -puN drivers/pci/pci.c~pci_device_state drivers/pci/pci.c
> > --- linux-2.6.16-rc3/drivers/pci/pci.c~pci_device_state 2006-02-14
> > 13:59:25.000000000 +0800
> > +++ linux-2.6.16-rc3-root/drivers/pci/pci.c 2006-02-14 14:00:12.000000000
> > +0800
> > @@ -532,6 +532,7 @@ pci_disable_device(struct pci_dev *dev)
> > pci_write_config_word(dev, PCI_COMMAND, pci_command);
> > }
> > dev->is_busmaster = 0;
> > + dev->current_state = PCI_UNKNOWN;
> >
> > pcibios_disable_device(dev);
> > dev->is_enabled = 0;
> > _
>
> waaah.
>
> For a long time my laptop wouldn't suspend because something in the
> ehci_hcd module is returning -EINVAL.
>
> ACPI: PCI interrupt for device 0000:00:1d.7 disabled
> ACPI (acpi_bus-0199): Device is not power manageable [20060210]
> ACPI: PCI Interrupt 0000:00:1d.7[D] -> GSI 23 (level, low) -> IRQ 22
> PCI: Setting latency timer of device 0000:00:1d.7 to 64
> Could not suspend device 0000:00:1d.7: error -22
>
> but a few weeks ago, suspend-to-ram started working. And I was happy.
>
> The above patch puts it back into not-working mode again.
>
> So I kinda liked the bug which you've gone and fixed.
>
> This shows that ehci can actually suspend and resume if it really wants to;
> problem is, it doesn't. How come?
OK, the failure is in:
suspend_device
->pci_device_suspend
->usb_hcd_pci_suspend
->pci_set_power_state
pci_set_power_state() is failing here:
if (state != PCI_D0 && dev->current_state > state)
return -EINVAL;
Because state=3 (PCI_D3hot) and current state=5 (PCI_UNKNOWN)
I note that usb_hcd_pci_suspend() calls pci_disable_device() _before_
calling pci_set_power_state(). I don't know if that's kosher, but it's
what caused this failure.
It all seems screwed up, or maybe it isn't. But I'll be dropping this patch.
> Oh, there's another bug. When the ehci driver fails in the above manner,
> the kernel backs out of the suspend attempt. But the kernel *sometimes*
> fails to restore power to an attached USB device (wireless mouse receiver).
> Unplugging and replugging the device fixes it.
This might be a consequence - I have no way to tell.
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