[Intel-gfx] [PATCH 05/50] drm/i915: Introduce struct intel_wakeref
Chris Wilson
chris at chris-wilson.co.uk
Fri Apr 12 08:53:25 UTC 2019
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 at chris-wilson.co.uk>
Cc; Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/Makefile.header-test | 3 +-
drivers/gpu/drm/i915/i915_drv.h | 3 +-
drivers/gpu/drm/i915/intel_wakeref.c | 62 ++++++++++
drivers/gpu/drm/i915/intel_wakeref.h | 133 ++++++++++++++++++++++
5 files changed, 199 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/i915/intel_wakeref.c
create mode 100644 drivers/gpu/drm/i915/intel_wakeref.h
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 40130cf5c003..233bad5e361f 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -50,6 +50,7 @@ i915-y += i915_drv.o \
intel_device_info.o \
intel_pm.o \
intel_runtime_pm.o \
+ intel_wakeref.o \
intel_uncore.o
# core library code
diff --git a/drivers/gpu/drm/i915/Makefile.header-test b/drivers/gpu/drm/i915/Makefile.header-test
index 96a5d90629ec..e6b3e7588860 100644
--- a/drivers/gpu/drm/i915/Makefile.header-test
+++ b/drivers/gpu/drm/i915/Makefile.header-test
@@ -31,7 +31,8 @@ header_test := \
intel_psr.h \
intel_sdvo.h \
intel_sprite.h \
- intel_tv.h
+ intel_tv.h \
+ intel_wakeref.h
quiet_cmd_header_test = HDRTEST $@
cmd_header_test = echo "\#include \"$(<F)\"" > $@
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index fad5306f07da..62a7e91acd7f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -74,6 +74,7 @@
#include "intel_opregion.h"
#include "intel_uc.h"
#include "intel_uncore.h"
+#include "intel_wakeref.h"
#include "intel_wopcm.h"
#include "i915_gem.h"
@@ -134,8 +135,6 @@ bool i915_error_injected(void);
__i915_printk(i915, i915_error_injected() ? KERN_DEBUG : KERN_ERR, \
fmt, ##__VA_ARGS__)
-typedef depot_stack_handle_t intel_wakeref_t;
-
enum hpd_pin {
HPD_NONE = 0,
HPD_TV = HPD_NONE, /* TV is known to be unreliable */
diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
new file mode 100644
index 000000000000..f4cfaa154303
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref.c
@@ -0,0 +1,62 @@
+/*
+ * 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);
+}
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
new file mode 100644
index 000000000000..a979d638344b
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -0,0 +1,133 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef INTEL_WAKEREF_H
+#define INTEL_WAKEREF_H
+
+#include <linux/atomic.h>
+#include <linux/mutex.h>
+#include <linux/stackdepot.h>
+
+struct drm_i915_private;
+
+typedef depot_stack_handle_t intel_wakeref_t;
+
+struct intel_wakeref {
+ atomic_t count;
+ struct mutex mutex;
+ intel_wakeref_t wakeref;
+};
+
+void __intel_wakeref_init(struct intel_wakeref *wf,
+ struct lock_class_key *key);
+#define intel_wakeref_init(wf) do { \
+ static struct lock_class_key __key; \
+ \
+ __intel_wakeref_init((wf), &__key); \
+} while (0)
+
+int __intel_wakeref_get_first(struct drm_i915_private *i915,
+ struct intel_wakeref *wf,
+ int (*fn)(struct intel_wakeref *wf));
+int __intel_wakeref_put_last(struct drm_i915_private *i915,
+ struct intel_wakeref *wf,
+ int (*fn)(struct intel_wakeref *wf));
+
+/**
+ * intel_wakeref_get: Acquire the wakeref
+ * @i915: the drm_i915_private device
+ * @wf: the wakeref
+ * @fn: callback for acquired the wakeref, called only on first acquire.
+ *
+ * Acquire a hold on the wakeref. The first user to do so, will acquire
+ * the runtime pm wakeref and then call the @fn underneath the wakeref
+ * mutex.
+ *
+ * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
+ * will be released and the acquisition unwound, and an error reported.
+ *
+ * Returns: 0 if the wakeref was acquired successfully, or a negative error
+ * code otherwise.
+ */
+static inline int
+intel_wakeref_get(struct drm_i915_private *i915,
+ struct intel_wakeref *wf,
+ int (*fn)(struct intel_wakeref *wf))
+{
+ if (unlikely(!atomic_inc_not_zero(&wf->count)))
+ return __intel_wakeref_get_first(i915, wf, fn);
+
+ return 0;
+}
+
+/**
+ * intel_wakeref_put: Release the wakeref
+ * @i915: the drm_i915_private device
+ * @wf: the wakeref
+ * @fn: callback for releasing the wakeref, called only on final release.
+ *
+ * Release our hold on the wakeref. When there are no more users,
+ * the runtime pm wakeref will be released after the @fn callback is called
+ * underneath the wakeref mutex.
+ *
+ * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
+ * is retained and an error reported.
+ *
+ * Returns: 0 if the wakeref was released successfully, or a negative error
+ * code otherwise.
+ */
+static inline int
+intel_wakeref_put(struct drm_i915_private *i915,
+ struct intel_wakeref *wf,
+ int (*fn)(struct intel_wakeref *wf))
+{
+ if (atomic_dec_and_mutex_lock(&wf->count, &wf->mutex))
+ return __intel_wakeref_put_last(i915, wf, fn);
+
+ return 0;
+}
+
+/**
+ * intel_wakeref_lock: Lock the wakeref (mutex)
+ * @wf: the wakeref
+ *
+ * Locks the wakeref to prevent it being acquired or released. New users
+ * can still adjust the counter, but the wakeref itself (and callback)
+ * cannot be acquired or released.
+ */
+static inline void
+intel_wakeref_lock(struct intel_wakeref *wf)
+ __acquires(wf->mutex)
+{
+ mutex_lock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_unlock: Unlock the wakeref
+ * @wf: the wakeref
+ *
+ * Releases a previously acquired intel_wakeref_lock().
+ */
+static inline void
+intel_wakeref_unlock(struct intel_wakeref *wf)
+ __releases(wf->mutex)
+{
+ mutex_unlock(&wf->mutex);
+}
+
+/**
+ * intel_wakeref_active: Query whether the wakeref is currently held
+ * @wf: the wakeref
+ *
+ * Returns: true if the wakeref is currently held.
+ */
+static inline bool
+intel_wakeref_active(struct intel_wakeref *wf)
+{
+ return atomic_read(&wf->count);
+}
+
+#endif /* INTEL_WAKEREF_H */
--
2.20.1
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