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SubjectRe: [Resend][PATCH] PCI PM: Read device power state from register after updating it
On Mon, 5 Oct 2009 00:48:40 +0200
"Rafael J. Wysocki" <> wrote:

> From: Rafael J. Wysocki <>
> After attempting to change the power state of a PCI device
> pci_raw_set_power_state() doesn't check if the value it wrote into
> the device's PCI_PM_CTRL register has been stored in there, but
> unconditionally modifies the device's current_state field to reflect
> the change. This may cause problems to happen if the power state of
> the device hasn't been changed in fact, because it will make the PCI
> PM core make a wrong assumption.
> To prevent such situations from happening modify
> pci_raw_set_power_state() so that it reads the device's PCI_PM_CTRL
> register after writing into it and uses the value read from the
> register to update the device's current_state field. Also make it
> print a message saying that the device refused to change its power
> state as requested (returning an error code in such cases would cause
> suspend regressions to appear on some systems, where device drivers'
> suspend routines return error codes if pci_set_power_state() fails).
> Signed-off-by: Rafael J. Wysocki <>

Applied to my for-linus branch, thanks.

Jesse Barnes, Intel Open Source Technology Center

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