[PATCH v2] drm/exynos: add vm_ops to specific gem mmaper

[Inki Dae]

Changelog v2:
call mutex_lock before drm_vm_open_locked is called.

Changelog v1:
This patch makes it takes a reference to gem object when
specific gem mmap is requested. For this, it sets
dev->driver->gem_vm_ops to vma->vm_ops.

And this patch is based on exynos-drm-next-iommu branch of
        git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos

Signed-off-by: Inki Dae <inki....@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.p...@samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c |   23 ++++++++++++++++++++++-
 1 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c 
b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 50d73f1..de524d9 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -372,10 +372,13 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
        struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
        struct exynos_drm_gem_buf *buffer;
        unsigned long vm_size;
+       int ret;
 
        DRM_DEBUG_KMS("%s\n", __FILE__);
 
        vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
+       vma->vm_private_data = obj;
+       vma->vm_ops = obj->dev->driver->gem_vm_ops;
 
        update_vm_cache_attr(exynos_gem_obj, vma);
 
@@ -391,9 +394,25 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
        if (vm_size > buffer->size)
                return -EINVAL;
 
-       return dma_mmap_attrs(obj->dev->dev, vma, buffer->kvaddr,
+       ret = dma_mmap_attrs(obj->dev->dev, vma, buffer->kvaddr,
                                buffer->dma_addr, buffer->size,
                                &buffer->dma_attrs);
+       if (ret < 0) {
+               DRM_ERROR("failed to mmap.\n");
+               return ret;
+       }
+
+       /*
+        * take a reference to this mapping of the object. And this reference
+        * is unreferenced by the corresponding vm_close call.
+        */
+       drm_gem_object_reference(obj);
+
+       mutex_lock(&obj->dev->struct_mutex);
+       drm_vm_open_locked(obj->dev, vma);
+       mutex_unlock(&obj->dev->struct_mutex);
+
+       return 0;
 }
 
 static const struct file_operations exynos_drm_gem_fops = {
@@ -426,6 +445,8 @@ int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void 
*data,
        addr = vm_mmap(obj->filp, 0, args->size,
                        PROT_READ | PROT_WRITE, MAP_SHARED, 0);
 
+       /* restore it to drm_file object. */
+       obj->filp->private_data = file_priv;
        drm_gem_object_unreference_unlocked(obj);
 
        if (IS_ERR((void *)addr))
-- 
1.7.4.1

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