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commit5694ba13b0upstream. For a device with no Power Management Capability, pci_power_up() previously returned 0 (success) if the platform was able to put the device in D0, which led to pci_set_full_power_state() trying to read PCI_PM_CTRL, even though it doesn't exist. Since dev->pm_cap == 0 in this case, pci_set_full_power_state() actually read the wrong register, interpreted it as PCI_PM_CTRL, and corrupted dev->current_state. This led to messages like this in some cases: pci 0000:01:00.0: Refused to change power state from D3hot to D0 To prevent this, make pci_power_up() always return a negative failure code if the device lacks a Power Management Capability, even if non-PCI platform power management has been able to put the device in D0. The failure will prevent pci_set_full_power_state() from trying to access PCI_PM_CTRL. Fixes:e200904b27("PCI/PM: Split pci_power_up()") Link: https://lore.kernel.org/r/20230824013738.1894965-1-chenfeiyang@loongson.cn Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: "Rafael J. Wysocki" <rafael@kernel.org> Cc: stable@vger.kernel.org # v5.19+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.