[lkml]   [2009]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    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

     \ /
      Last update: 2009-10-06 18:11    [W:0.020 / U:13.308 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site