The counter goes to zero at the start of the parking cycle, but the
wakeref itself is held until the end. Likewise, the counter becomes one
at the end of the unparking, but the wakeref is taken first. If we check
the wakeref instead of the counter, we include the unpark/unparking time
as intel_wakeref_is_active(), and do not spuriously declare inactive if
we fail to park (i.e. the parking and wakeref drop is postponed).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190503115225.30831-2-chris@chris-wilson.co.uk
For controlling runtime pm of the GT and engines, we would like to have
a callback to do extra work the first time we wake up and the last time
we drop the wakeref. This first/last access needs serialisation and so
we encompass a mutex with the regular intel_wakeref_t tracker.
v2: Drop the _once naming and report the errors.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc; Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190424200717.1686-1-chris@chris-wilson.co.uk
