drivers/char/drm/i915_mem.c - fp2-dev/kernel/msm - Gitiles

 /* i915_mem.c -- Simple agp/fb memory manager for i915 -*- linux-c -*-
  */
 /*
  * Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  */

 #include "drmP.h"
 #include "drm.h"
 #include "i915_drm.h"
 #include "i915_drv.h"

 /* This memory manager is integrated into the global/local lru
  * mechanisms used by the clients.  Specifically, it operates by
  * setting the 'in_use' fields of the global LRU to indicate whether
  * this region is privately allocated to a client.
  *
  * This does require the client to actually respect that field.
  *
  * Currently no effort is made to allocate 'private' memory in any
  * clever way - the LRU information isn't used to determine which
  * block to allocate, and the ring is drained prior to allocations --
  * in other words allocation is expensive.
  */
 static void mark_block(struct drm_device * dev, struct mem_block *p, int in_use)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;
 	struct drm_tex_region *list;
 	unsigned shift, nr;
 	unsigned start;
 	unsigned end;
 	unsigned i;
 	int age;

 	shift = dev_priv->tex_lru_log_granularity;
 	nr = I915_NR_TEX_REGIONS;

 	start = p->start >> shift;
 	end = (p->start + p->size - 1) >> shift;

 	age = ++sarea_priv->texAge;
 	list = sarea_priv->texList;

 	/* Mark the regions with the new flag and update their age.  Move
 	 * them to head of list to preserve LRU semantics.
 	 */
 	for (i = start; i <= end; i++) {
 		list[i].in_use = in_use;
 		list[i].age = age;

 		/* remove_from_list(i)
 		 */
 		list[(unsigned)list[i].next].prev = list[i].prev;
 		list[(unsigned)list[i].prev].next = list[i].next;

 		/* insert_at_head(list, i)
 		 */
 		list[i].prev = nr;
 		list[i].next = list[nr].next;
 		list[(unsigned)list[nr].next].prev = i;
 		list[nr].next = i;
 	}
 }

 /* Very simple allocator for agp memory, working on a static range
  * already mapped into each client's address space.
  */

 static struct mem_block *split_block(struct mem_block *p, int start, int size,
 				     DRMFILE filp)
 {
 	/* Maybe cut off the start of an existing block */
 	if (start > p->start) {
 		struct mem_block *newblock =
 		    drm_alloc(sizeof(*newblock), DRM_MEM_BUFLISTS);
 		if (!newblock)
 			goto out;
 		newblock->start = start;
 		newblock->size = p->size - (start - p->start);
 		newblock->filp = NULL;
 		newblock->next = p->next;
 		newblock->prev = p;
 		p->next->prev = newblock;
 		p->next = newblock;
 		p->size -= newblock->size;
 		p = newblock;
 	}

 	/* Maybe cut off the end of an existing block */
 	if (size < p->size) {
 		struct mem_block *newblock =
 		    drm_alloc(sizeof(*newblock), DRM_MEM_BUFLISTS);
 		if (!newblock)
 			goto out;
 		newblock->start = start + size;
 		newblock->size = p->size - size;
 		newblock->filp = NULL;
 		newblock->next = p->next;
 		newblock->prev = p;
 		p->next->prev = newblock;
 		p->next = newblock;
 		p->size = size;
 	}

       out:
 	/* Our block is in the middle */
 	p->filp = filp;
 	return p;
 }

 static struct mem_block *alloc_block(struct mem_block *heap, int size,
 				     int align2, DRMFILE filp)
 {
 	struct mem_block *p;
 	int mask = (1 << align2) - 1;

 	for (p = heap->next; p != heap; p = p->next) {
 		int start = (p->start + mask) & ~mask;
 		if (p->filp == NULL && start + size <= p->start + p->size)
 			return split_block(p, start, size, filp);
 	}

 	return NULL;
 }

 static struct mem_block *find_block(struct mem_block *heap, int start)
 {
 	struct mem_block *p;

 	for (p = heap->next; p != heap; p = p->next)
 		if (p->start == start)
 			return p;

 	return NULL;
 }

 static void free_block(struct mem_block *p)
 {
 	p->filp = NULL;

 	/* Assumes a single contiguous range.  Needs a special filp in
 	 * 'heap' to stop it being subsumed.
 	 */
 	if (p->next->filp == NULL) {
 		struct mem_block *q = p->next;
 		p->size += q->size;
 		p->next = q->next;
 		p->next->prev = p;
 		drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
 	}

 	if (p->prev->filp == NULL) {
 		struct mem_block *q = p->prev;
 		q->size += p->size;
 		q->next = p->next;
 		q->next->prev = q;
 		drm_free(p, sizeof(*q), DRM_MEM_BUFLISTS);
 	}
 }

 /* Initialize.  How to check for an uninitialized heap?
  */
 static int init_heap(struct mem_block **heap, int start, int size)
 {
 	struct mem_block *blocks = drm_alloc(sizeof(*blocks), DRM_MEM_BUFLISTS);

 	if (!blocks)
 		return -ENOMEM;

 	*heap = drm_alloc(sizeof(**heap), DRM_MEM_BUFLISTS);
 	if (!*heap) {
 		drm_free(blocks, sizeof(*blocks), DRM_MEM_BUFLISTS);
 		return -ENOMEM;
 	}

 	blocks->start = start;
 	blocks->size = size;
 	blocks->filp = NULL;
 	blocks->next = blocks->prev = *heap;

 	memset(*heap, 0, sizeof(**heap));
 	(*heap)->filp = (DRMFILE) - 1;
 	(*heap)->next = (*heap)->prev = blocks;
 	return 0;
 }

 /* Free all blocks associated with the releasing file.
  */
 void i915_mem_release(struct drm_device * dev, DRMFILE filp, struct mem_block *heap)
 {
 	struct mem_block *p;

 	if (!heap || !heap->next)
 		return;

 	for (p = heap->next; p != heap; p = p->next) {
 		if (p->filp == filp) {
 			p->filp = NULL;
 			mark_block(dev, p, 0);
 		}
 	}

 	/* Assumes a single contiguous range.  Needs a special filp in
 	 * 'heap' to stop it being subsumed.
 	 */
 	for (p = heap->next; p != heap; p = p->next) {
 		while (p->filp == NULL && p->next->filp == NULL) {
 			struct mem_block *q = p->next;
 			p->size += q->size;
 			p->next = q->next;
 			p->next->prev = p;
 			drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
 		}
 	}
 }

 /* Shutdown.
  */
 void i915_mem_takedown(struct mem_block **heap)
 {
 	struct mem_block *p;

 	if (!*heap)
 		return;

 	for (p = (*heap)->next; p != *heap;) {
 		struct mem_block *q = p;
 		p = p->next;
 		drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
 	}

 	drm_free(*heap, sizeof(**heap), DRM_MEM_BUFLISTS);
 	*heap = NULL;
 }

 static struct mem_block **get_heap(drm_i915_private_t * dev_priv, int region)
 {
 	switch (region) {
 	case I915_MEM_REGION_AGP:
 		return &dev_priv->agp_heap;
 	default:
 		return NULL;
 	}
 }

 /* IOCTL HANDLERS */

 int i915_mem_alloc(DRM_IOCTL_ARGS)
 {
 	DRM_DEVICE;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	drm_i915_mem_alloc_t alloc;
 	struct mem_block *block, **heap;

 	if (!dev_priv) {
 		DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
 		return DRM_ERR(EINVAL);
 	}

 	DRM_COPY_FROM_USER_IOCTL(alloc, (drm_i915_mem_alloc_t __user *) data,
 				 sizeof(alloc));

 	heap = get_heap(dev_priv, alloc.region);
 	if (!heap || !*heap)
 		return DRM_ERR(EFAULT);

 	/* Make things easier on ourselves: all allocations at least
 	 * 4k aligned.
 	 */
 	if (alloc.alignment < 12)
 		alloc.alignment = 12;

 	block = alloc_block(*heap, alloc.size, alloc.alignment, filp);

 	if (!block)
 		return DRM_ERR(ENOMEM);

 	mark_block(dev, block, 1);

 	if (DRM_COPY_TO_USER(alloc.region_offset, &block->start, sizeof(int))) {
 		DRM_ERROR("copy_to_user\n");
 		return DRM_ERR(EFAULT);
 	}

 	return 0;
 }

 int i915_mem_free(DRM_IOCTL_ARGS)
 {
 	DRM_DEVICE;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	drm_i915_mem_free_t memfree;
 	struct mem_block *block, **heap;

 	if (!dev_priv) {
 		DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
 		return DRM_ERR(EINVAL);
 	}

 	DRM_COPY_FROM_USER_IOCTL(memfree, (drm_i915_mem_free_t __user *) data,
 				 sizeof(memfree));

 	heap = get_heap(dev_priv, memfree.region);
 	if (!heap || !*heap)
 		return DRM_ERR(EFAULT);

 	block = find_block(*heap, memfree.region_offset);
 	if (!block)
 		return DRM_ERR(EFAULT);

 	if (block->filp != filp)
 		return DRM_ERR(EPERM);

 	mark_block(dev, block, 0);
 	free_block(block);
 	return 0;
 }

 int i915_mem_init_heap(DRM_IOCTL_ARGS)
 {
 	DRM_DEVICE;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	drm_i915_mem_init_heap_t initheap;
 	struct mem_block **heap;

 	if (!dev_priv) {
 		DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
 		return DRM_ERR(EINVAL);
 	}

 	DRM_COPY_FROM_USER_IOCTL(initheap,
 				 (drm_i915_mem_init_heap_t __user *) data,
 				 sizeof(initheap));

 	heap = get_heap(dev_priv, initheap.region);
 	if (!heap)
 		return DRM_ERR(EFAULT);

 	if (*heap) {
 		DRM_ERROR("heap already initialized?");
 		return DRM_ERR(EFAULT);
 	}

 	return init_heap(heap, initheap.start, initheap.size);
 }

 int i915_mem_destroy_heap( DRM_IOCTL_ARGS )
 {
 	DRM_DEVICE;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	drm_i915_mem_destroy_heap_t destroyheap;
 	struct mem_block **heap;

 	if ( !dev_priv ) {
 		DRM_ERROR( "%s called with no initialization\n", __FUNCTION__ );
 		return DRM_ERR(EINVAL);
 	}

 	DRM_COPY_FROM_USER_IOCTL( destroyheap, (drm_i915_mem_destroy_heap_t *)data,
 				  sizeof(destroyheap) );

 	heap = get_heap( dev_priv, destroyheap.region );
 	if (!heap) {
 		DRM_ERROR("get_heap failed");
 		return DRM_ERR(EFAULT);
 	}

 	if (!*heap) {
 		DRM_ERROR("heap not initialized?");
 		return DRM_ERR(EFAULT);
 	}

 	i915_mem_takedown( heap );
 	return 0;
 }
	/* i915_mem.c -- Simple agp/fb memory manager for i915 -- linux-c --
	*/
	/*
	* Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sub license, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice (including the
	* next paragraph) shall be included in all copies or substantial portions
	* of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
	* IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
	* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
	* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
	* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	*/

	#include "drmP.h"
	#include "drm.h"
	#include "i915_drm.h"
	#include "i915_drv.h"

	/* This memory manager is integrated into the global/local lru
	* mechanisms used by the clients. Specifically, it operates by
	* setting the 'in_use' fields of the global LRU to indicate whether
	* this region is privately allocated to a client.
	*
	* This does require the client to actually respect that field.
	*
	* Currently no effort is made to allocate 'private' memory in any
	* clever way - the LRU information isn't used to determine which
	* block to allocate, and the ring is drained prior to allocations --
	* in other words allocation is expensive.
	*/
	static void mark_block(struct drm_device * dev, struct mem_block *p, int in_use)
	{
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;
	struct drm_tex_region *list;
	unsigned shift, nr;
	unsigned start;
	unsigned end;
	unsigned i;
	int age;

	shift = dev_priv->tex_lru_log_granularity;
	nr = I915_NR_TEX_REGIONS;

	start = p->start >> shift;
	end = (p->start + p->size - 1) >> shift;

	age = ++sarea_priv->texAge;
	list = sarea_priv->texList;

	/* Mark the regions with the new flag and update their age. Move
	* them to head of list to preserve LRU semantics.
	*/
	for (i = start; i <= end; i++) {
	list[i].in_use = in_use;
	list[i].age = age;

	/* remove_from_list(i)
	*/
	list[(unsigned)list[i].next].prev = list[i].prev;
	list[(unsigned)list[i].prev].next = list[i].next;

	/* insert_at_head(list, i)
	*/
	list[i].prev = nr;
	list[i].next = list[nr].next;
	list[(unsigned)list[nr].next].prev = i;
	list[nr].next = i;
	}
	}

	/* Very simple allocator for agp memory, working on a static range
	* already mapped into each client's address space.
	*/

	static struct mem_block split_block(struct mem_block p, int start, int size,
	DRMFILE filp)
	{
	/* Maybe cut off the start of an existing block */
	if (start > p->start) {
	struct mem_block *newblock =
	drm_alloc(sizeof(*newblock), DRM_MEM_BUFLISTS);
	if (!newblock)
	goto out;
	newblock->start = start;
	newblock->size = p->size - (start - p->start);
	newblock->filp = NULL;
	newblock->next = p->next;
	newblock->prev = p;
	p->next->prev = newblock;
	p->next = newblock;
	p->size -= newblock->size;
	p = newblock;
	}

	/* Maybe cut off the end of an existing block */
	if (size < p->size) {
	struct mem_block *newblock =
	drm_alloc(sizeof(*newblock), DRM_MEM_BUFLISTS);
	if (!newblock)
	goto out;
	newblock->start = start + size;
	newblock->size = p->size - size;
	newblock->filp = NULL;
	newblock->next = p->next;
	newblock->prev = p;
	p->next->prev = newblock;
	p->next = newblock;
	p->size = size;
	}

	out:
	/* Our block is in the middle */
	p->filp = filp;
	return p;
	}

	static struct mem_block alloc_block(struct mem_block heap, int size,
	int align2, DRMFILE filp)
	{
	struct mem_block *p;
	int mask = (1 << align2) - 1;

	for (p = heap->next; p != heap; p = p->next) {
	int start = (p->start + mask) & ~mask;
	if (p->filp == NULL && start + size <= p->start + p->size)
	return split_block(p, start, size, filp);
	}

	return NULL;
	}

	static struct mem_block find_block(struct mem_block heap, int start)
	{
	struct mem_block *p;

	for (p = heap->next; p != heap; p = p->next)
	if (p->start == start)
	return p;

	return NULL;
	}

	static void free_block(struct mem_block *p)
	{
	p->filp = NULL;

	/* Assumes a single contiguous range. Needs a special filp in
	* 'heap' to stop it being subsumed.
	*/
	if (p->next->filp == NULL) {
	struct mem_block *q = p->next;
	p->size += q->size;
	p->next = q->next;
	p->next->prev = p;
	drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
	}

	if (p->prev->filp == NULL) {
	struct mem_block *q = p->prev;
	q->size += p->size;
	q->next = p->next;
	q->next->prev = q;
	drm_free(p, sizeof(*q), DRM_MEM_BUFLISTS);
	}
	}

	/* Initialize. How to check for an uninitialized heap?
	*/
	static int init_heap(struct mem_block **heap, int start, int size)
	{
	struct mem_block blocks = drm_alloc(sizeof(blocks), DRM_MEM_BUFLISTS);

	if (!blocks)
	return -ENOMEM;

	heap = drm_alloc(sizeof(*heap), DRM_MEM_BUFLISTS);
	if (!*heap) {
	drm_free(blocks, sizeof(*blocks), DRM_MEM_BUFLISTS);
	return -ENOMEM;
	}

	blocks->start = start;
	blocks->size = size;
	blocks->filp = NULL;
	blocks->next = blocks->prev = *heap;

	memset(heap, 0, sizeof(*heap));
	(*heap)->filp = (DRMFILE) - 1;
	(heap)->next = (heap)->prev = blocks;
	return 0;
	}

	/* Free all blocks associated with the releasing file.
	*/
	void i915_mem_release(struct drm_device * dev, DRMFILE filp, struct mem_block *heap)
	{
	struct mem_block *p;

	if (!heap \|\| !heap->next)
	return;

	for (p = heap->next; p != heap; p = p->next) {
	if (p->filp == filp) {
	p->filp = NULL;
	mark_block(dev, p, 0);
	}
	}

	/* Assumes a single contiguous range. Needs a special filp in
	* 'heap' to stop it being subsumed.
	*/
	for (p = heap->next; p != heap; p = p->next) {
	while (p->filp == NULL && p->next->filp == NULL) {
	struct mem_block *q = p->next;
	p->size += q->size;
	p->next = q->next;
	p->next->prev = p;
	drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
	}
	}
	}

	/* Shutdown.
	*/
	void i915_mem_takedown(struct mem_block **heap)
	{
	struct mem_block *p;

	if (!*heap)
	return;

	for (p = (heap)->next; p != heap;) {
	struct mem_block *q = p;
	p = p->next;
	drm_free(q, sizeof(*q), DRM_MEM_BUFLISTS);
	}

	drm_free(heap, sizeof(*heap), DRM_MEM_BUFLISTS);
	*heap = NULL;
	}

	static struct mem_block *get_heap(drm_i915_private_t dev_priv, int region)
	{
	switch (region) {
	case I915_MEM_REGION_AGP:
	return &dev_priv->agp_heap;
	default:
	return NULL;
	}
	}

	/* IOCTL HANDLERS */

	int i915_mem_alloc(DRM_IOCTL_ARGS)
	{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_alloc_t alloc;
	struct mem_block block, *heap;

	if (!dev_priv) {
	DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
	return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL(alloc, (drm_i915_mem_alloc_t __user *) data,
	sizeof(alloc));

	heap = get_heap(dev_priv, alloc.region);
	if (!heap \|\| !*heap)
	return DRM_ERR(EFAULT);

	/* Make things easier on ourselves: all allocations at least
	* 4k aligned.
	*/
	if (alloc.alignment < 12)
	alloc.alignment = 12;

	block = alloc_block(*heap, alloc.size, alloc.alignment, filp);

	if (!block)
	return DRM_ERR(ENOMEM);

	mark_block(dev, block, 1);

	if (DRM_COPY_TO_USER(alloc.region_offset, &block->start, sizeof(int))) {
	DRM_ERROR("copy_to_user\n");
	return DRM_ERR(EFAULT);
	}

	return 0;
	}

	int i915_mem_free(DRM_IOCTL_ARGS)
	{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_free_t memfree;
	struct mem_block block, *heap;

	if (!dev_priv) {
	DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
	return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL(memfree, (drm_i915_mem_free_t __user *) data,
	sizeof(memfree));

	heap = get_heap(dev_priv, memfree.region);
	if (!heap \|\| !*heap)
	return DRM_ERR(EFAULT);

	block = find_block(*heap, memfree.region_offset);
	if (!block)
	return DRM_ERR(EFAULT);

	if (block->filp != filp)
	return DRM_ERR(EPERM);

	mark_block(dev, block, 0);
	free_block(block);
	return 0;
	}

	int i915_mem_init_heap(DRM_IOCTL_ARGS)
	{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_init_heap_t initheap;
	struct mem_block **heap;

	if (!dev_priv) {
	DRM_ERROR("%s called with no initialization\n", __FUNCTION__);
	return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL(initheap,
	(drm_i915_mem_init_heap_t __user *) data,
	sizeof(initheap));

	heap = get_heap(dev_priv, initheap.region);
	if (!heap)
	return DRM_ERR(EFAULT);

	if (*heap) {
	DRM_ERROR("heap already initialized?");
	return DRM_ERR(EFAULT);
	}

	return init_heap(heap, initheap.start, initheap.size);
	}

	int i915_mem_destroy_heap( DRM_IOCTL_ARGS )
	{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_destroy_heap_t destroyheap;
	struct mem_block **heap;

	if ( !dev_priv ) {
	DRM_ERROR( "%s called with no initialization\n", __FUNCTION__ );
	return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL( destroyheap, (drm_i915_mem_destroy_heap_t *)data,
	sizeof(destroyheap) );

	heap = get_heap( dev_priv, destroyheap.region );
	if (!heap) {
	DRM_ERROR("get_heap failed");
	return DRM_ERR(EFAULT);
	}

	if (!*heap) {
	DRM_ERROR("heap not initialized?");
	return DRM_ERR(EFAULT);
	}

	i915_mem_takedown( heap );
	return 0;
	}