[PATCH v5 2/9] drm/hisilicon/hibmc: Add video memory management

Rongrong Zou zourongrong at gmail.com
Wed Oct 26 02:36:59 UTC 2016


Hibmc have 32m video memory which can be accessed through PCIe by host,
we use ttm to manage these memory.

Signed-off-by: Rongrong Zou <zourongrong at gmail.com>
---
 drivers/gpu/drm/hisilicon/hibmc/Kconfig         |   1 +
 drivers/gpu/drm/hisilicon/hibmc/Makefile        |   2 +-
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c |  12 +
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h |  46 +++
 drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c     | 490 ++++++++++++++++++++++++
 5 files changed, 550 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c

diff --git a/drivers/gpu/drm/hisilicon/hibmc/Kconfig b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
index a9af90d..bcb8c18 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/Kconfig
+++ b/drivers/gpu/drm/hisilicon/hibmc/Kconfig
@@ -1,6 +1,7 @@
 config DRM_HISI_HIBMC
 	tristate "DRM Support for Hisilicon Hibmc"
 	depends on DRM && PCI
+	select DRM_TTM
 
 	help
 	  Choose this option if you have a Hisilicon Hibmc soc chipset.
diff --git a/drivers/gpu/drm/hisilicon/hibmc/Makefile b/drivers/gpu/drm/hisilicon/hibmc/Makefile
index 97cf4a0..d5c40b8 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/Makefile
+++ b/drivers/gpu/drm/hisilicon/hibmc/Makefile
@@ -1,5 +1,5 @@
 ccflags-y := -Iinclude/drm
-hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_power.o
+hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_power.o hibmc_ttm.o
 
 obj-$(CONFIG_DRM_HISI_HIBMC)	+=hibmc-drm.o
 #obj-y	+= hibmc-drm.o
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index 4669d42..81f4301 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -31,6 +31,7 @@
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= drm_compat_ioctl,
 #endif
+	.mmap		= hibmc_mmap,
 	.poll		= drm_poll,
 	.read		= drm_read,
 	.llseek		= no_llseek,
@@ -46,6 +47,8 @@ static void hibmc_disable_vblank(struct drm_device *dev, unsigned int pipe)
 }
 
 static struct drm_driver hibmc_driver = {
+	.driver_features	= DRIVER_GEM,
+
 	.fops			= &hibmc_fops,
 	.name			= "hibmc",
 	.date			= "20160828",
@@ -55,6 +58,10 @@ static void hibmc_disable_vblank(struct drm_device *dev, unsigned int pipe)
 	.get_vblank_counter	= drm_vblank_no_hw_counter,
 	.enable_vblank		= hibmc_enable_vblank,
 	.disable_vblank		= hibmc_disable_vblank,
+	.gem_free_object_unlocked = hibmc_gem_free_object,
+	.dumb_create            = hibmc_dumb_create,
+	.dumb_map_offset        = hibmc_dumb_mmap_offset,
+	.dumb_destroy           = drm_gem_dumb_destroy,
 };
 
 static int hibmc_pm_suspend(struct device *dev)
@@ -163,6 +170,7 @@ static int hibmc_unload(struct drm_device *dev)
 {
 	struct hibmc_drm_device *hidev = dev->dev_private;
 
+	hibmc_mm_fini(hidev);
 	hibmc_hw_fini(hidev);
 	dev->dev_private = NULL;
 	return 0;
@@ -183,6 +191,10 @@ static int hibmc_load(struct drm_device *dev, unsigned long flags)
 	if (ret)
 		goto err;
 
+	ret = hibmc_mm_init(hidev);
+	if (ret)
+		goto err;
+
 	return 0;
 
 err:
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
index 0037341..db8d80e 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
@@ -20,6 +20,8 @@
 #define HIBMC_DRM_DRV_H
 
 #include <drm/drmP.h>
+#include <drm/ttm/ttm_bo_driver.h>
+#include <drm/drm_gem.h>
 
 struct hibmc_drm_device {
 	/* hw */
@@ -30,6 +32,50 @@ struct hibmc_drm_device {
 
 	/* drm */
 	struct drm_device  *dev;
+
+	/* ttm */
+	struct {
+		struct drm_global_reference mem_global_ref;
+		struct ttm_bo_global_ref bo_global_ref;
+		struct ttm_bo_device bdev;
+		bool initialized;
+	} ttm;
+
+	bool mm_inited;
 };
 
+struct hibmc_bo {
+	struct ttm_buffer_object bo;
+	struct ttm_placement placement;
+	struct ttm_bo_kmap_obj kmap;
+	struct drm_gem_object gem;
+	struct ttm_place placements[3];
+	int pin_count;
+};
+
+static inline struct hibmc_bo *hibmc_bo(struct ttm_buffer_object *bo)
+{
+	return container_of(bo, struct hibmc_bo, bo);
+}
+
+static inline struct hibmc_bo *gem_to_hibmc_bo(struct drm_gem_object *gem)
+{
+	return container_of(gem, struct hibmc_bo, gem);
+}
+
+#define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT)
+
+int hibmc_gem_create(struct drm_device *dev, u32 size, bool iskernel,
+		     struct drm_gem_object **obj);
+
+int hibmc_mm_init(struct hibmc_drm_device *hibmc);
+void hibmc_mm_fini(struct hibmc_drm_device *hibmc);
+int hibmc_bo_pin(struct hibmc_bo *bo, u32 pl_flag, u64 *gpu_addr);
+void hibmc_gem_free_object(struct drm_gem_object *obj);
+int hibmc_dumb_create(struct drm_file *file, struct drm_device *dev,
+		      struct drm_mode_create_dumb *args);
+int hibmc_dumb_mmap_offset(struct drm_file *file, struct drm_device *dev,
+			   u32 handle, u64 *offset);
+int hibmc_mmap(struct file *filp, struct vm_area_struct *vma);
+
 #endif
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
new file mode 100644
index 0000000..0802ebd
--- /dev/null
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
@@ -0,0 +1,490 @@
+/* Hisilicon Hibmc SoC drm driver
+ *
+ * Based on the bochs drm driver.
+ *
+ * Copyright (c) 2016 Huawei Limited.
+ *
+ * Author:
+ *	Rongrong Zou <zourongrong at huawei.com>
+ *	Rongrong Zou <zourongrong at gmail.com>
+ *	Jianhua Li <lijianhua at huawei.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include "hibmc_drm_drv.h"
+#include <ttm/ttm_page_alloc.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_atomic_helper.h>
+
+static inline struct hibmc_drm_device *
+hibmc_bdev(struct ttm_bo_device *bd)
+{
+	return container_of(bd, struct hibmc_drm_device, ttm.bdev);
+}
+
+static int
+hibmc_ttm_mem_global_init(struct drm_global_reference *ref)
+{
+	return ttm_mem_global_init(ref->object);
+}
+
+static void
+hibmc_ttm_mem_global_release(struct drm_global_reference *ref)
+{
+	ttm_mem_global_release(ref->object);
+}
+
+static int hibmc_ttm_global_init(struct hibmc_drm_device *hibmc)
+{
+	struct drm_global_reference *global_ref;
+	int r;
+
+	global_ref = &hibmc->ttm.mem_global_ref;
+	global_ref->global_type = DRM_GLOBAL_TTM_MEM;
+	global_ref->size = sizeof(struct ttm_mem_global);
+	global_ref->init = &hibmc_ttm_mem_global_init;
+	global_ref->release = &hibmc_ttm_mem_global_release;
+	r = drm_global_item_ref(global_ref);
+	if (r != 0) {
+		DRM_ERROR("Failed setting up TTM memory accounting subsystem.\n"
+			 );
+		return r;
+	}
+
+	hibmc->ttm.bo_global_ref.mem_glob =
+		hibmc->ttm.mem_global_ref.object;
+	global_ref = &hibmc->ttm.bo_global_ref.ref;
+	global_ref->global_type = DRM_GLOBAL_TTM_BO;
+	global_ref->size = sizeof(struct ttm_bo_global);
+	global_ref->init = &ttm_bo_global_init;
+	global_ref->release = &ttm_bo_global_release;
+	r = drm_global_item_ref(global_ref);
+	if (r != 0) {
+		DRM_ERROR("Failed setting up TTM BO subsystem.\n");
+		drm_global_item_unref(&hibmc->ttm.mem_global_ref);
+		return r;
+	}
+	return 0;
+}
+
+static void
+hibmc_ttm_global_release(struct hibmc_drm_device *hibmc)
+{
+	if (!hibmc->ttm.mem_global_ref.release)
+		return;
+
+	drm_global_item_unref(&hibmc->ttm.bo_global_ref.ref);
+	drm_global_item_unref(&hibmc->ttm.mem_global_ref);
+	hibmc->ttm.mem_global_ref.release = NULL;
+}
+
+static void hibmc_bo_ttm_destroy(struct ttm_buffer_object *tbo)
+{
+	struct hibmc_bo *bo;
+
+	bo = container_of(tbo, struct hibmc_bo, bo);
+
+	drm_gem_object_release(&bo->gem);
+	kfree(bo);
+}
+
+static bool hibmc_ttm_bo_is_hibmc_bo(struct ttm_buffer_object *bo)
+{
+	if (bo->destroy == &hibmc_bo_ttm_destroy)
+		return true;
+	return false;
+}
+
+static int
+hibmc_bo_init_mem_type(struct ttm_bo_device *bdev, u32 type,
+		       struct ttm_mem_type_manager *man)
+{
+	switch (type) {
+	case TTM_PL_SYSTEM:
+		man->flags = TTM_MEMTYPE_FLAG_MAPPABLE;
+		man->available_caching = TTM_PL_MASK_CACHING;
+		man->default_caching = TTM_PL_FLAG_CACHED;
+		break;
+	case TTM_PL_VRAM:
+		man->func = &ttm_bo_manager_func;
+		man->flags = TTM_MEMTYPE_FLAG_FIXED |
+			TTM_MEMTYPE_FLAG_MAPPABLE;
+		man->available_caching = TTM_PL_FLAG_UNCACHED |
+			TTM_PL_FLAG_WC;
+		man->default_caching = TTM_PL_FLAG_WC;
+		break;
+	default:
+		DRM_ERROR("Unsupported memory type %u\n", type);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+void hibmc_ttm_placement(struct hibmc_bo *bo, int domain)
+{
+	u32 c = 0;
+	u32 i;
+
+	bo->placement.placement = bo->placements;
+	bo->placement.busy_placement = bo->placements;
+	if (domain & TTM_PL_FLAG_VRAM)
+		bo->placements[c++].flags = TTM_PL_FLAG_WC |
+		TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_VRAM;
+	if (domain & TTM_PL_FLAG_SYSTEM)
+		bo->placements[c++].flags = TTM_PL_MASK_CACHING |
+		TTM_PL_FLAG_SYSTEM;
+	if (!c)
+		bo->placements[c++].flags = TTM_PL_MASK_CACHING |
+		TTM_PL_FLAG_SYSTEM;
+
+	bo->placement.num_placement = c;
+	bo->placement.num_busy_placement = c;
+	for (i = 0; i < c; ++i) {
+		bo->placements[i].fpfn = 0;
+		bo->placements[i].lpfn = 0;
+	}
+}
+
+static void
+hibmc_bo_evict_flags(struct ttm_buffer_object *bo, struct ttm_placement *pl)
+{
+	struct hibmc_bo *hibmcbo = hibmc_bo(bo);
+
+	if (!hibmc_ttm_bo_is_hibmc_bo(bo))
+		return;
+
+	hibmc_ttm_placement(hibmcbo, TTM_PL_FLAG_SYSTEM);
+	*pl = hibmcbo->placement;
+}
+
+static int hibmc_bo_verify_access(struct ttm_buffer_object *bo,
+				  struct file *filp)
+{
+	struct hibmc_bo *hibmcbo = hibmc_bo(bo);
+
+	return drm_vma_node_verify_access(&hibmcbo->gem.vma_node,
+					  filp->private_data);
+}
+
+static int hibmc_ttm_io_mem_reserve(struct ttm_bo_device *bdev,
+				    struct ttm_mem_reg *mem)
+{
+	struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
+	struct hibmc_drm_device *hibmc = hibmc_bdev(bdev);
+
+	mem->bus.addr = NULL;
+	mem->bus.offset = 0;
+	mem->bus.size = mem->num_pages << PAGE_SHIFT;
+	mem->bus.base = 0;
+	mem->bus.is_iomem = false;
+	if (!(man->flags & TTM_MEMTYPE_FLAG_MAPPABLE))
+		return -EINVAL;
+	switch (mem->mem_type) {
+	case TTM_PL_SYSTEM:
+		/* system memory */
+		return 0;
+	case TTM_PL_VRAM:
+		mem->bus.offset = mem->start << PAGE_SHIFT;
+		mem->bus.base = pci_resource_start(hibmc->dev->pdev, 0);
+		mem->bus.is_iomem = true;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void hibmc_ttm_io_mem_free(struct ttm_bo_device *bdev,
+				  struct ttm_mem_reg *mem)
+{
+}
+
+static void hibmc_ttm_backend_destroy(struct ttm_tt *tt)
+{
+	ttm_tt_fini(tt);
+	kfree(tt);
+}
+
+static struct ttm_backend_func hibmc_tt_backend_func = {
+	.destroy = &hibmc_ttm_backend_destroy,
+};
+
+static struct ttm_tt *hibmc_ttm_tt_create(struct ttm_bo_device *bdev,
+					  unsigned long size,
+					  u32 page_flags,
+					  struct page *dummy_read_page)
+{
+	struct ttm_tt *tt;
+
+	tt = kzalloc(sizeof(*tt), GFP_KERNEL);
+	if (!tt)
+		return NULL;
+	tt->func = &hibmc_tt_backend_func;
+	if (ttm_tt_init(tt, bdev, size, page_flags, dummy_read_page)) {
+		kfree(tt);
+		return NULL;
+	}
+	return tt;
+}
+
+static int hibmc_ttm_tt_populate(struct ttm_tt *ttm)
+{
+	return ttm_pool_populate(ttm);
+}
+
+static void hibmc_ttm_tt_unpopulate(struct ttm_tt *ttm)
+{
+	ttm_pool_unpopulate(ttm);
+}
+
+struct ttm_bo_driver hibmc_bo_driver = {
+	.ttm_tt_create		= hibmc_ttm_tt_create,
+	.ttm_tt_populate	= hibmc_ttm_tt_populate,
+	.ttm_tt_unpopulate	= hibmc_ttm_tt_unpopulate,
+	.init_mem_type		= hibmc_bo_init_mem_type,
+	.evict_flags		= hibmc_bo_evict_flags,
+	.move			= NULL,
+	.verify_access		= hibmc_bo_verify_access,
+	.io_mem_reserve		= &hibmc_ttm_io_mem_reserve,
+	.io_mem_free		= &hibmc_ttm_io_mem_free,
+	.lru_tail		= &ttm_bo_default_lru_tail,
+	.swap_lru_tail		= &ttm_bo_default_swap_lru_tail,
+};
+
+int hibmc_mm_init(struct hibmc_drm_device *hibmc)
+{
+	int ret;
+	struct drm_device *dev = hibmc->dev;
+	struct ttm_bo_device *bdev = &hibmc->ttm.bdev;
+
+	ret = hibmc_ttm_global_init(hibmc);
+	if (ret)
+		return ret;
+
+	ret = ttm_bo_device_init(&hibmc->ttm.bdev,
+				 hibmc->ttm.bo_global_ref.ref.object,
+				 &hibmc_bo_driver,
+				 dev->anon_inode->i_mapping,
+				 DRM_FILE_PAGE_OFFSET,
+				 true);
+	if (ret) {
+		DRM_ERROR("Error initialising bo driver; %d\n", ret);
+		return ret;
+	}
+
+	ret = ttm_bo_init_mm(bdev, TTM_PL_VRAM,
+			     hibmc->fb_size >> PAGE_SHIFT);
+	if (ret) {
+		DRM_ERROR("Failed ttm VRAM init: %d\n", ret);
+		return ret;
+	}
+
+	hibmc->mm_inited = true;
+	return 0;
+}
+
+void hibmc_mm_fini(struct hibmc_drm_device *hibmc)
+{
+	if (!hibmc->mm_inited)
+		return;
+
+	ttm_bo_device_release(&hibmc->ttm.bdev);
+	hibmc_ttm_global_release(hibmc);
+	hibmc->mm_inited = false;
+}
+
+int hibmc_bo_create(struct drm_device *dev, int size, int align,
+		    u32 flags, struct hibmc_bo **phibmcbo)
+{
+	struct hibmc_drm_device *hibmc = dev->dev_private;
+	struct hibmc_bo *hibmcbo;
+	size_t acc_size;
+	int ret;
+
+	hibmcbo = kzalloc(sizeof(*hibmcbo), GFP_KERNEL);
+	if (!hibmcbo)
+		return -ENOMEM;
+
+	ret = drm_gem_object_init(dev, &hibmcbo->gem, size);
+	if (ret) {
+		kfree(hibmcbo);
+		return ret;
+	}
+
+	hibmcbo->bo.bdev = &hibmc->ttm.bdev;
+
+	hibmc_ttm_placement(hibmcbo, TTM_PL_FLAG_VRAM | TTM_PL_FLAG_SYSTEM);
+
+	acc_size = ttm_bo_dma_acc_size(&hibmc->ttm.bdev, size,
+				       sizeof(struct hibmc_bo));
+
+	ret = ttm_bo_init(&hibmc->ttm.bdev, &hibmcbo->bo, size,
+			  ttm_bo_type_device, &hibmcbo->placement,
+			  align >> PAGE_SHIFT, false, NULL, acc_size,
+			  NULL, NULL, hibmc_bo_ttm_destroy);
+	if (ret)
+		return ret;
+
+	*phibmcbo = hibmcbo;
+	return 0;
+}
+
+static inline u64 hibmc_bo_gpu_offset(struct hibmc_bo *bo)
+{
+	return bo->bo.offset;
+}
+
+int hibmc_bo_pin(struct hibmc_bo *bo, u32 pl_flag, u64 *gpu_addr)
+{
+	int i, ret;
+
+	if (bo->pin_count) {
+		bo->pin_count++;
+		if (gpu_addr)
+			*gpu_addr = hibmc_bo_gpu_offset(bo);
+	}
+
+	hibmc_ttm_placement(bo, pl_flag);
+	for (i = 0; i < bo->placement.num_placement; i++)
+		bo->placements[i].flags |= TTM_PL_FLAG_NO_EVICT;
+	ret = ttm_bo_validate(&bo->bo, &bo->placement, false, false);
+	if (ret)
+		return ret;
+
+	bo->pin_count = 1;
+	if (gpu_addr)
+		*gpu_addr = hibmc_bo_gpu_offset(bo);
+	return 0;
+}
+
+int hibmc_bo_push_sysram(struct hibmc_bo *bo)
+{
+	int i, ret;
+
+	if (!bo->pin_count) {
+		DRM_ERROR("unpin bad %p\n", bo);
+		return 0;
+	}
+	bo->pin_count--;
+	if (bo->pin_count)
+		return 0;
+
+	if (bo->kmap.virtual)
+		ttm_bo_kunmap(&bo->kmap);
+
+	hibmc_ttm_placement(bo, TTM_PL_FLAG_SYSTEM);
+	for (i = 0; i < bo->placement.num_placement ; i++)
+		bo->placements[i].flags |= TTM_PL_FLAG_NO_EVICT;
+
+	ret = ttm_bo_validate(&bo->bo, &bo->placement, false, false);
+	if (ret) {
+		DRM_ERROR("pushing to VRAM failed\n");
+		return ret;
+	}
+	return 0;
+}
+
+int hibmc_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct drm_file *file_priv;
+	struct hibmc_drm_device *hibmc;
+
+	if (unlikely(vma->vm_pgoff < DRM_FILE_PAGE_OFFSET))
+		return -EINVAL;
+
+	file_priv = filp->private_data;
+	hibmc = file_priv->minor->dev->dev_private;
+	return ttm_bo_mmap(filp, vma, &hibmc->ttm.bdev);
+}
+
+int hibmc_gem_create(struct drm_device *dev, u32 size, bool iskernel,
+		     struct drm_gem_object **obj)
+{
+	struct hibmc_bo *hibmcbo;
+	int ret;
+
+	*obj = NULL;
+
+	size = PAGE_ALIGN(size);
+	if (size == 0)
+		return -EINVAL;
+
+	ret = hibmc_bo_create(dev, size, 0, 0, &hibmcbo);
+	if (ret) {
+		if (ret != -ERESTARTSYS)
+			DRM_ERROR("failed to allocate GEM object\n");
+		return ret;
+	}
+	*obj = &hibmcbo->gem;
+	return 0;
+}
+
+int hibmc_dumb_create(struct drm_file *file, struct drm_device *dev,
+		      struct drm_mode_create_dumb *args)
+{
+	struct drm_gem_object *gobj;
+	u32 handle;
+	int ret;
+
+	args->pitch = ALIGN(args->width * ((args->bpp + 7) / 8), 16);
+	args->size = args->pitch * args->height;
+
+	ret = hibmc_gem_create(dev, args->size, false,
+			       &gobj);
+	if (ret)
+		return ret;
+
+	ret = drm_gem_handle_create(file, gobj, &handle);
+	drm_gem_object_unreference_unlocked(gobj);
+	if (ret)
+		return ret;
+
+	args->handle = handle;
+	return 0;
+}
+
+static void hibmc_bo_unref(struct hibmc_bo **bo)
+{
+	struct ttm_buffer_object *tbo;
+
+	if ((*bo) == NULL)
+		return;
+
+	tbo = &((*bo)->bo);
+	ttm_bo_unref(&tbo);
+	*bo = NULL;
+}
+
+void hibmc_gem_free_object(struct drm_gem_object *obj)
+{
+	struct hibmc_bo *hibmcbo = gem_to_hibmc_bo(obj);
+
+	hibmc_bo_unref(&hibmcbo);
+}
+
+static u64 hibmc_bo_mmap_offset(struct hibmc_bo *bo)
+{
+	return drm_vma_node_offset_addr(&bo->bo.vma_node);
+}
+
+int hibmc_dumb_mmap_offset(struct drm_file *file, struct drm_device *dev,
+			   u32 handle, u64 *offset)
+{
+	struct drm_gem_object *obj;
+	struct hibmc_bo *bo;
+
+	obj = drm_gem_object_lookup(file, handle);
+	if (!obj)
+		return -ENOENT;
+
+	bo = gem_to_hibmc_bo(obj);
+	*offset = hibmc_bo_mmap_offset(bo);
+
+	drm_gem_object_unreference_unlocked(obj);
+	return 0;
+}
-- 
1.9.1



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