On Wed, 2009-02-04 at 01:59 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@xxxxxxx>
>
> Make pci_legacy_suspend() save the state of the device if it is
> in PCI_UNKNOWN after its suspend callback has run and warn only if
> the power state of the device has been changed by its suspend
> callback.
>
> Also, use WARN_ONCE(), which is more useful, in pci_legacy_suspend(),
> so that the name of the offending function is printed.
>
> Additionaly, remove the unnecessary line of code setting
> pci_dev->state_saved.
Minor nit: Should the warning be preceeded by a message ? The reason is,
right now, all we get is a backtrace, it doesn't actually tell you which
device or driver caused it which makes it pretty pointless.
I think you should add a printk(KERN_ERR... just before that which gives
those informations along with a little blurb along the lines of "driver
changed device state without saving config space state").
> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> Reported-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/pci/pci-driver.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/drivers/pci/pci-driver.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci-driver.c
> +++ linux-2.6/drivers/pci/pci-driver.c
> @@ -355,6 +355,8 @@ static int pci_legacy_suspend(struct dev
> int i = 0;
>
> if (drv && drv->suspend) {
> + pci_power_t prev = pci_dev->current_state;
> +
> pci_dev->state_saved = false;
>
> i = drv->suspend(pci_dev, state);
> @@ -365,12 +367,16 @@ static int pci_legacy_suspend(struct dev
> if (pci_dev->state_saved)
> goto Fixup;
>
> - if (WARN_ON_ONCE(pci_dev->current_state != PCI_D0))
> + if (pci_dev->current_state != PCI_D0
> + && pci_dev->current_state != PCI_UNKNOWN) {
> + WARN_ONCE(pci_dev->current_state != prev,
> + "PCI PM: Device state not saved by %pF\n",
> + drv->suspend);
> goto Fixup;
> + }
> }
>
> pci_save_state(pci_dev);
> - pci_dev->state_saved = true;
> /*
> * This is for compatibility with existing code with legacy PM support.
> */
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