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    SubjectRe: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended
    On Mar 09 2016 or thereabouts, Mika Westerberg wrote:
    > On Tue, Mar 08, 2016 at 03:03:23PM -0800, Dmitry Torokhov wrote:
    > > On ACPI-based systems ACPI power domain code runtime resumes device before
    > > calling suspend method, which ensures that i2c-hid suspend code starts with
    > > device not in low-power state and with interrupts enabled.
    > >
    > > On other systems, especially if device is not a part of any power domain,
    > > we may end up calling driver's system-level suspend routine while the
    > > device is runtime-suspended (with controller in presumably low power state
    > > and interrupts disabled). This will result in interrupts being essentially
    > > disabled twice, and we will only re-enable them after both system resume
    > > and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
    > > i2c_hid_hwreset() and that only works properly if interrupts are enabled.
    > >
    > > Also if device is runtime-suspended driver's suspend code may fail if it
    > > tries to issue I/O requests.
    > >
    > > Let's fix it by runtime-resuming the device if we need to run HID driver's
    > > suspend code and also disabling interrupts only if device is not already
    > > runtime-suspended. Also on resume we mark the device as running at full
    > > power (since that is what resetting will do to it).
    > >
    > > Signed-off-by: Doug Anderson <dianders@chromium.org>
    > > Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
    >
    > Tested on a couple of Intel Skylake and Baytrail based systems and power
    > management of I2C connected HID devices still seems to work just fine.
    >
    > Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

    Well, I have completely no way of testing this myself, and I blindly
    trust Mika, Dmitry and the others for doing the right thing :).

    Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

    Cheers,
    Benjamin

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