[PATCH v7 2/7] drm/hisilicon/hibmc: Add video memory management
Sean Paul
seanpaul at chromium.org
Wed Nov 16 07:52:43 PST 2016
On Wed, Nov 16, 2016 at 8:43 AM, Rongrong Zou <zourongrong at gmail.com> wrote:
> 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>
Reviewed-by: Sean Paul <seanpaul at chromium.org>
> ---
> drivers/gpu/drm/hisilicon/hibmc/Makefile | 2 +-
> drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 14 +
> drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h | 41 ++
> drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c | 485 ++++++++++++++++++++++++
> 4 files changed, 541 insertions(+), 1 deletion(-)
> create mode 100644 drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
>
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/Makefile b/drivers/gpu/drm/hisilicon/hibmc/Makefile
> index 47962a0..19ed0ef 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/Makefile
> +++ b/drivers/gpu/drm/hisilicon/hibmc/Makefile
> @@ -1,4 +1,4 @@
> ccflags-y := -Iinclude/drm
> -hibmc-drm-y := hibmc_drm_drv.o
> +hibmc-drm-y := hibmc_drm_drv.o hibmc_ttm.o
>
> obj-$(CONFIG_DRM_HISI_HIBMC) += 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 6d20580..521f69f 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> @@ -28,6 +28,7 @@
> .release = drm_release,
> .unlocked_ioctl = drm_ioctl,
> .compat_ioctl = drm_compat_ioctl,
> + .mmap = hibmc_mmap,
> .poll = drm_poll,
> .read = drm_read,
> .llseek = no_llseek,
> @@ -43,6 +44,7 @@ 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",
> @@ -52,6 +54,10 @@ 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)
> @@ -194,6 +200,10 @@ static int hibmc_hw_init(struct hibmc_drm_private *priv)
>
> static int hibmc_unload(struct drm_device *dev)
> {
> + struct hibmc_drm_private *priv = dev->dev_private;
> +
> + hibmc_mm_fini(priv);
> + dev->dev_private = NULL;
> return 0;
> }
>
> @@ -214,6 +224,10 @@ static int hibmc_load(struct drm_device *dev)
> if (ret)
> goto err;
>
> + ret = hibmc_mm_init(priv);
> + 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 840cd5a..dcd304d 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/drm_gem.h>
> +#include <drm/ttm/ttm_bo_driver.h>
>
> struct hibmc_drm_private {
> /* hw */
> @@ -31,11 +33,50 @@ struct hibmc_drm_private {
> /* drm */
> struct drm_device *dev;
>
> + /* ttm */
> + struct drm_global_reference mem_global_ref;
> + struct ttm_bo_global_ref bo_global_ref;
> + struct ttm_bo_device bdev;
> + bool initialized;
> +
> + 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);
> +}
> +
> void hibmc_set_power_mode(struct hibmc_drm_private *priv,
> unsigned int power_mode);
> void hibmc_set_current_gate(struct hibmc_drm_private *priv,
> unsigned int gate);
>
> +int hibmc_gem_create(struct drm_device *dev, u32 size, bool iskernel,
> + struct drm_gem_object **obj);
> +int hibmc_mm_init(struct hibmc_drm_private *hibmc);
> +void hibmc_mm_fini(struct hibmc_drm_private *hibmc);
> +int hibmc_bo_pin(struct hibmc_bo *bo, u32 pl_flag, u64 *gpu_addr);
> +int hibmc_bo_unpin(struct hibmc_bo *bo);
> +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..036d3ac
> --- /dev/null
> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c
> @@ -0,0 +1,485 @@
> +/* 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 <ttm/ttm_page_alloc.h>
> +
> +#include "hibmc_drm_drv.h"
> +
> +#define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT)
> +
> +static inline struct hibmc_drm_private *
> +hibmc_bdev(struct ttm_bo_device *bd)
> +{
> + return container_of(bd, struct hibmc_drm_private, 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_private *hibmc)
> +{
> + int ret;
> +
> + hibmc->mem_global_ref.global_type = DRM_GLOBAL_TTM_MEM;
> + hibmc->mem_global_ref.size = sizeof(struct ttm_mem_global);
> + hibmc->mem_global_ref.init = &hibmc_ttm_mem_global_init;
> + hibmc->mem_global_ref.release = &hibmc_ttm_mem_global_release;
> + ret = drm_global_item_ref(&hibmc->mem_global_ref);
> + if (ret) {
> + DRM_ERROR("could not get ref on ttm global: %d\n", ret);
> + return ret;
> + }
> +
> + hibmc->bo_global_ref.mem_glob =
> + hibmc->mem_global_ref.object;
> + hibmc->bo_global_ref.ref.global_type = DRM_GLOBAL_TTM_BO;
> + hibmc->bo_global_ref.ref.size = sizeof(struct ttm_bo_global);
> + hibmc->bo_global_ref.ref.init = &ttm_bo_global_init;
> + hibmc->bo_global_ref.ref.release = &ttm_bo_global_release;
> + ret = drm_global_item_ref(&hibmc->bo_global_ref.ref);
> + if (ret) {
> + DRM_ERROR("failed setting up TTM BO subsystem: %d\n", ret);
> + drm_global_item_unref(&hibmc->mem_global_ref);
> + return ret;
> + }
> + return 0;
> +}
> +
> +static void
> +hibmc_ttm_global_release(struct hibmc_drm_private *hibmc)
> +{
> + drm_global_item_unref(&hibmc->bo_global_ref.ref);
> + drm_global_item_unref(&hibmc->mem_global_ref);
> + hibmc->mem_global_ref.release = NULL;
> +}
> +
> +static void hibmc_bo_ttm_destroy(struct ttm_buffer_object *tbo)
> +{
> + struct hibmc_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)
> +{
> + return bo->destroy == &hibmc_bo_ttm_destroy;
> +}
> +
> +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 count = 0;
> + u32 i;
> +
> + bo->placement.placement = bo->placements;
> + bo->placement.busy_placement = bo->placements;
> + if (domain & TTM_PL_FLAG_VRAM)
> + bo->placements[count++].flags = TTM_PL_FLAG_WC |
> + TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_VRAM;
> + if (domain & TTM_PL_FLAG_SYSTEM)
> + bo->placements[count++].flags = TTM_PL_MASK_CACHING |
> + TTM_PL_FLAG_SYSTEM;
> + if (!count)
> + bo->placements[count++].flags = TTM_PL_MASK_CACHING |
> + TTM_PL_FLAG_SYSTEM;
> +
> + bo->placement.num_placement = count;
> + bo->placement.num_busy_placement = count;
> + for (i = 0; i < count; 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_private *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_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;
> + int ret;
> +
> + tt = kzalloc(sizeof(*tt), GFP_KERNEL);
> + if (!tt) {
> + DRM_ERROR("failed to allocate ttm_tt\n");
> + return NULL;
> + }
> + tt->func = &hibmc_tt_backend_func;
> + ret = ttm_tt_init(tt, bdev, size, page_flags, dummy_read_page);
> + if (ret) {
> + DRM_ERROR("failed to initialize ttm_tt: %d\n", ret);
> + 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 = NULL,
> + .lru_tail = &ttm_bo_default_lru_tail,
> + .swap_lru_tail = &ttm_bo_default_swap_lru_tail,
> +};
> +
> +int hibmc_mm_init(struct hibmc_drm_private *hibmc)
> +{
> + int ret;
> + struct drm_device *dev = hibmc->dev;
> + struct ttm_bo_device *bdev = &hibmc->bdev;
> +
> + ret = hibmc_ttm_global_init(hibmc);
> + if (ret)
> + return ret;
> +
> + ret = ttm_bo_device_init(&hibmc->bdev,
> + hibmc->bo_global_ref.ref.object,
> + &hibmc_bo_driver,
> + dev->anon_inode->i_mapping,
> + DRM_FILE_PAGE_OFFSET,
> + true);
> + if (ret) {
> + hibmc_ttm_global_release(hibmc);
> + DRM_ERROR("error initializing bo driver: %d\n", ret);
> + return ret;
> + }
> +
> + ret = ttm_bo_init_mm(bdev, TTM_PL_VRAM,
> + hibmc->fb_size >> PAGE_SHIFT);
> + if (ret) {
> + hibmc_ttm_global_release(hibmc);
> + DRM_ERROR("failed ttm VRAM init: %d\n", ret);
> + return ret;
> + }
> +
> + hibmc->mm_inited = true;
> + return 0;
> +}
> +
> +void hibmc_mm_fini(struct hibmc_drm_private *hibmc)
> +{
> + if (!hibmc->mm_inited)
> + return;
> +
> + ttm_bo_device_release(&hibmc->bdev);
> + hibmc_ttm_global_release(hibmc);
> + hibmc->mm_inited = false;
> +}
> +
> +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;
> +}
> +
> +int hibmc_bo_create(struct drm_device *dev, int size, int align,
> + u32 flags, struct hibmc_bo **phibmcbo)
> +{
> + struct hibmc_drm_private *hibmc = dev->dev_private;
> + struct hibmc_bo *hibmcbo;
> + size_t acc_size;
> + int ret;
> +
> + hibmcbo = kzalloc(sizeof(*hibmcbo), GFP_KERNEL);
> + if (!hibmcbo) {
> + DRM_ERROR("failed to allocate hibmcbo\n");
> + return -ENOMEM;
> + }
> + ret = drm_gem_object_init(dev, &hibmcbo->gem, size);
> + if (ret) {
> + DRM_ERROR("failed to initialize drm gem object: %d\n", ret);
> + kfree(hibmcbo);
> + return ret;
> + }
> +
> + hibmcbo->bo.bdev = &hibmc->bdev;
> +
> + hibmc_ttm_placement(hibmcbo, TTM_PL_FLAG_VRAM | TTM_PL_FLAG_SYSTEM);
> +
> + acc_size = ttm_bo_dma_acc_size(&hibmc->bdev, size,
> + sizeof(struct hibmc_bo));
> +
> + ret = ttm_bo_init(&hibmc->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) {
> + hibmc_bo_unref(&hibmcbo);
> + DRM_ERROR("failed to initialize ttm_bo: %d\n", ret);
> + return ret;
> + }
> +
> + *phibmcbo = hibmcbo;
> + return 0;
> +}
> +
> +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 = bo->bo.offset;
> + return 0;
> + }
> +
> + 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 = bo->bo.offset;
> + return 0;
> +}
> +
> +int hibmc_bo_unpin(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;
> +
> + 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("validate failed for unpin: %d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +int hibmc_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> + struct drm_file *file_priv;
> + struct hibmc_drm_private *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->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) {
> + DRM_ERROR("error: zero size\n");
> + return -EINVAL;
> + }
> +
> + ret = hibmc_bo_create(dev, size, 0, 0, &hibmcbo);
> + if (ret) {
> + if (ret != -ERESTARTSYS)
> + DRM_ERROR("failed to allocate GEM object: %d\n", ret);
> + 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 * DIV_ROUND_UP(args->bpp, 8), 16);
> + args->size = args->pitch * args->height;
> +
> + ret = hibmc_gem_create(dev, args->size, false,
> + &gobj);
> + if (ret) {
> + DRM_ERROR("failed to create GEM object: %d\n", ret);
> + return ret;
> + }
> +
> + ret = drm_gem_handle_create(file, gobj, &handle);
> + drm_gem_object_unreference_unlocked(gobj);
> + if (ret) {
> + DRM_ERROR("failed to unreference GEM object: %d\n", ret);
> + return ret;
> + }
> +
> + args->handle = handle;
> + return 0;
> +}
> +
> +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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