Re: [PATCH 02/10] drm/i915: Introduce i915_gem_object_get_dma_address()

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 04/02/16 09:30, ankitprasad.r.sharma@intel.com wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
>
> This utility function is a companion to i915_gem_object_get_page() that
> uses the same cached iterator for the scatterlist to perform fast
> sequential lookup of the dma address associated with any page within the
> object.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_drv.h | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 65a2cd0..e4c25c6 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2947,6 +2947,23 @@ static inline int __sg_page_count(struct scatterlist *sg)
>   struct page *
>   i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, int n);
>
> +static inline dma_addr_t
> +i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, int n)
> +{
> +	if (n < obj->get_page.last) {
> +		obj->get_page.sg = obj->pages->sgl;
> +		obj->get_page.last = 0;
> +	}
> +
> +	while (obj->get_page.last + __sg_page_count(obj->get_page.sg) <= n) {
> +		obj->get_page.last += __sg_page_count(obj->get_page.sg++);
> +		if (unlikely(sg_is_chain(obj->get_page.sg)))
> +			obj->get_page.sg = sg_chain_ptr(obj->get_page.sg);
> +	}
> +
> +	return sg_dma_address(obj->get_page.sg) + ((n - obj->get_page.last) << PAGE_SHIFT);
> +}
> +
>   static inline struct page *
>   i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n)
>   {
>

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
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