ae860a19f3
If a driver uses DPM_FLAG_SMART_SUSPEND and the device is already runtime suspended when hibernate is started PCI core skips runtime resuming the device but still clears pci_dev->state_saved. After the hibernation image is written pci_pm_thaw_noirq() makes sure subsequent thaw phases for the device are also skipped leaving it runtime suspended with pci_dev->state_saved == false. When the device is eventually runtime resumed pci_pm_runtime_resume() restores config space by calling pci_restore_standard_config(), however because pci_dev->state_saved == false pci_restore_state() never actually restores the config space leaving the device in a state that is not what the driver might expect. For example here is what happens for intel-lpss I2C devices once the hibernation snapshot is taken: intel-lpss 0000:00:15.0: power state changed by ACPI to D0 intel-lpss 0000:00:1e.0: power state changed by ACPI to D3cold video LNXVIDEO:00: Restoring backlight state PM: hibernation exit i2c_designware i2c_designware.1: Unknown Synopsys component type: 0xffffffff i2c_designware i2c_designware.0: Unknown Synopsys component type: 0xffffffff i2c_designware i2c_designware.1: timeout in disabling adapter i2c_designware i2c_designware.0: timeout in disabling adapter Since PCI config space is not restored the device is still in D3hot making MMIO register reads return 0xffffffff. Fix this by clearing pci_dev->state_saved only if we actually end up runtime resuming the device. Fixes: c4b65157aeef (PCI / PM: Take SMART_SUSPEND driver flag into account) Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: 4.15+ <stable@vger.kernel.org> # 4.15+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.