Re: [PATCH 06/24] drm/i915: Convert the dmabuf object to use the new i915_gem_object_ops

[Ben Widawsky <ben@bwidawsk.net>]

On Tue,  4 Sep 2012 21:02:58 +0100
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> By providing a callback for when we need to bind the pages, and then
> release them again later, we can shorten the amount of time we hold the
> foreign pages mapped and pinned, and importantly the dmabuf objects then
> behave as any other normal object with respect to the shrinker and
> memory management.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
with nitpicks below:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_drv.h        |    1 -
>  drivers/gpu/drm/i915/i915_gem.c        |   10 ++++----
>  drivers/gpu/drm/i915/i915_gem_dmabuf.c |   44 ++++++++++++++++++++++----------
>  drivers/gpu/drm/i915/i915_gem_gtt.c    |    4 +--
>  4 files changed, 37 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 1a714fa..a86f50d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -998,7 +998,6 @@ struct drm_i915_gem_object {
>  	int pages_pin_count;
>  
>  	/* prime dma-buf support */
> -	struct sg_table *sg_table;
>  	void *dma_buf_vmapping;
>  	int vmapping_count;
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 06589a9..58075e3 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1692,7 +1692,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
>  {
>  	const struct drm_i915_gem_object_ops *ops = obj->ops;
>  
> -	if (obj->sg_table || obj->pages == NULL)
> +	if (obj->pages == NULL)
>  		return 0;
>  
>  	BUG_ON(obj->gtt_space);
> @@ -1838,7 +1838,7 @@ i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
>  	const struct drm_i915_gem_object_ops *ops = obj->ops;
>  	int ret;
>  
> -	if (obj->sg_table || obj->pages)
> +	if (obj->pages)
>  		return 0;
>  
>  	BUG_ON(obj->pages_pin_count);
> @@ -3731,9 +3731,6 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
>  
>  	trace_i915_gem_object_destroy(obj);
>  
> -	if (gem_obj->import_attach)
> -		drm_prime_gem_destroy(gem_obj, obj->sg_table);
> -
>  	if (obj->phys_obj)
>  		i915_gem_detach_phys_object(dev, obj);
>  
> @@ -3755,6 +3752,9 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
>  
>  	BUG_ON(obj->pages);
>  
> +	if (obj->base.import_attach)
> +		drm_prime_gem_destroy(&obj->base, NULL);
> +
>  	drm_gem_object_release(&obj->base);
>  	i915_gem_info_remove_obj(dev_priv, obj->base.size);
>  

Was the order in which destroy happens moved intentionally?

> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> index 4bb1b94..ca3497e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -82,7 +82,8 @@ out:
>  }
>  
>  static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
> -			    struct sg_table *sg, enum dma_data_direction dir)
> +				   struct sg_table *sg,
> +				   enum dma_data_direction dir)
>  {
>  	dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
>  	sg_free_table(sg);

I thought we frown upon unnecessary whitespace fixes in patches which
have behavioral changes?

> @@ -228,11 +229,35 @@ struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
>  	return dma_buf_export(obj, &i915_dmabuf_ops, obj->base.size, 0600);
>  }
>  
> +static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
> +{
> +	struct sg_table *sg;
> +
> +	sg = dma_buf_map_attachment(obj->base.import_attach, DMA_BIDIRECTIONAL);
> +	if (IS_ERR(sg))
> +		return PTR_ERR(sg);
> +
> +	obj->pages = sg;
> +	obj->has_dma_mapping = true;
> +	return 0;
> +}
> +
> +static void i915_gem_object_put_pages_dmabuf(struct drm_i915_gem_object *obj)
> +{
> +	dma_buf_unmap_attachment(obj->base.import_attach,
> +				 obj->pages, DMA_BIDIRECTIONAL);
> +	obj->has_dma_mapping = false;
> +}
> +
> +static const struct drm_i915_gem_object_ops i915_gem_object_dmabuf_ops = {
> +	.get_pages = i915_gem_object_get_pages_dmabuf,
> +	.put_pages = i915_gem_object_put_pages_dmabuf,
> +};
> +
>  struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
>  					     struct dma_buf *dma_buf)
>  {
>  	struct dma_buf_attachment *attach;
> -	struct sg_table *sg;
>  	struct drm_i915_gem_object *obj;
>  	int ret;
>  
> @@ -251,34 +276,25 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
>  	if (IS_ERR(attach))
>  		return ERR_CAST(attach);
>  
> -	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
> -	if (IS_ERR(sg)) {
> -		ret = PTR_ERR(sg);
> -		goto fail_detach;
> -	}
>  
>  	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
>  	if (obj == NULL) {
>  		ret = -ENOMEM;
> -		goto fail_unmap;
> +		goto fail_detach;
>  	}
>  
>  	ret = drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
>  	if (ret) {
>  		kfree(obj);
> -		goto fail_unmap;
> +		goto fail_detach;
>  	}
>  
> -	obj->has_dma_mapping = true;
> -	obj->sg_table = sg;
> +	i915_gem_object_init(obj, &i915_gem_object_dmabuf_ops);
>  	obj->base.import_attach = attach;
>  
>  	return &obj->base;
>  
> -fail_unmap:
> -	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
>  fail_detach:
>  	dma_buf_detach(dma_buf, attach);
>  	return ERR_PTR(ret);
>  }
> -
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 6746109..c86dc59 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -234,7 +234,7 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
>  	}
>  
>  	i915_ppgtt_insert_sg_entries(ppgtt,
> -				     obj->sg_table ?: obj->pages,
> +				     obj->pages,
>  				     obj->gtt_space->start >> PAGE_SHIFT,
>  				     pte_flags);
>  }
> @@ -325,7 +325,7 @@ void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
>  	struct drm_device *dev = obj->base.dev;
>  	unsigned int agp_type = cache_level_to_agp_type(dev, cache_level);
>  
> -	intel_gtt_insert_sg_entries(obj->sg_table ?: obj->pages,
> +	intel_gtt_insert_sg_entries(obj->pages,
>  				    obj->gtt_space->start >> PAGE_SHIFT,
>  				    agp_type);
>  	obj->has_global_gtt_mapping = 1;



-- 
Ben Widawsky, Intel Open Source Technology Center