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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" <rjw@sisk.pl> wrote:

    > From: Rafael J. Wysocki <rjw@sisk.pl>
    >
    > 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 <rjw@sisk.pl>

    Applied to my for-linus branch, thanks.

    --
    Jesse Barnes, Intel Open Source Technology Center


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