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    SubjectRe: [PATCH 4.4 39/53] PCI/PM: Add needs_resume flag to avoid suspend complete optimization
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    On Mon, 2017-06-05 at 18:17 +0200, Greg Kroah-Hartman wrote:
    > 4.4-stable review patch. If anyone has any objections, please let me know.
    >
    > ------------------
    >
    > From: Imre Deak <imre.deak@intel.com>
    >
    > commit 4d071c3238987325b9e50e33051a40d1cce311cc upstream.
    >
    > Some drivers - like i915 - may not support the system suspend direct
    > complete optimization due to differences in their runtime and system
    > suspend sequence. Add a flag that when set resumes the device before
    > calling the driver's system suspend handlers which effectively disables
    > the optimization.
    >
    > Needed by a future patch fixing suspend/resume on i915.

    The patch for i915 isn't in this series, or even in mainline yet, so I
    don't think this belongs in stable yet. Also, based on the commit
    message (commit adfdf85d795f "drm/i915: Prevent the system suspend
    complete optimization") it appears that only 4.8 and later are affected
    by the bug.

    Ben.

    > Suggested by Rafael.
    >
    > Signed-off-by: Imre Deak <imre.deak@intel.com>
    > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    >
    > ---
    > drivers/pci/pci.c | 3 ++-
    > include/linux/pci.h | 5 +++++
    > 2 files changed, 7 insertions(+), 1 deletion(-)
    >
    > --- a/drivers/pci/pci.c
    > +++ b/drivers/pci/pci.c
    > @@ -2079,7 +2079,8 @@ bool pci_dev_keep_suspended(struct pci_d
    >
    > if (!pm_runtime_suspended(dev)
    > || pci_target_state(pci_dev) != pci_dev->current_state
    > - || platform_pci_need_resume(pci_dev))
    > + || platform_pci_need_resume(pci_dev)
    > + || (pci_dev->dev_flags & PCI_DEV_FLAGS_NEEDS_RESUME))
    > return false;
    >
    > /*
    > --- a/include/linux/pci.h
    > +++ b/include/linux/pci.h
    > @@ -182,6 +182,11 @@ enum pci_dev_flags {
    > PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7),
    > /* Get VPD from function 0 VPD */
    > PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
    > + /*
    > + * Resume before calling the driver's system suspend hooks, disabling
    > + * the direct_complete optimization.
    > + */
    > + PCI_DEV_FLAGS_NEEDS_RESUME = (__force pci_dev_flags_t) (1 << 11),
    > };
    >
    > enum pci_irq_reroute_variant {
    >
    >
    >

    --
    Ben Hutchings
    Software Developer, Codethink Ltd.


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