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drm/i915: Introduce struct intel_wakeref

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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
This commit is contained in:
Chris Wilson
2019-04-24 21:07:13 +01:00
parent 112ed2d31a
commit d91e657876
5 changed files with 198 additions and 3 deletions
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61
drivers/gpu/drm/i915/intel_wakeref.c Normal file
View File

@@ -0,0 +1,61 @@
/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#include "intel_drv.h"
#include "intel_wakeref.h"
int __intel_wakeref_get_first(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf))
{
/*
* Treat get/put as different subclasses, as we may need to run
* the put callback from under the shrinker and do not want to
* cross-contanimate that callback with any extra work performed
* upon acquiring the wakeref.
*/
mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
if (!atomic_read(&wf->count)) {
int err;
wf->wakeref = intel_runtime_pm_get(i915);
err = fn(wf);
if (unlikely(err)) {
intel_runtime_pm_put(i915, wf->wakeref);
mutex_unlock(&wf->mutex);
return err;
}
smp_mb__before_atomic(); /* release wf->count */
}
atomic_inc(&wf->count);
mutex_unlock(&wf->mutex);
return 0;
}
int __intel_wakeref_put_last(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf))
{
int err;
err = fn(wf);
if (likely(!err))
intel_runtime_pm_put(i915, wf->wakeref);
else
atomic_inc(&wf->count);
mutex_unlock(&wf->mutex);
return err;
}
void __intel_wakeref_init(struct intel_wakeref *wf, struct lock_class_key *key)
{
__mutex_init(&wf->mutex, "wakeref", key);
atomic_set(&wf->count, 0);
}