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Commit d91e6578 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Introduce struct intel_wakeref 



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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc; Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190424200717.1686-1-chris@chris-wilson.co.uk
parent 112ed2d3

drivers/gpu/drm/i915/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/gpu/drm/i915/Makefile.header-test

+2 −1
Original line number Diff line number Diff line
@@ -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)\"" > $@

drivers/gpu/drm/i915/i915_drv.h

+1 −2
Original line number Diff line number Diff line
@@ -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 */

drivers/gpu/drm/i915/intel_wakeref.c

0 → 100644
+61 −0
Original line number Diff line number Diff line 
/*

 * 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);

}

drivers/gpu/drm/i915/intel_wakeref.h

0 → 100644
+133 −0
Original line number Diff line number Diff line 
/*

 * 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 */