[Intel-gfx] [PATCH 06/21] drm/i915: introduce page_size members

[Chris Wilson]

Quoting Matthew Auld (2017-10-05 16:19:00)
>  static inline unsigned int i915_sg_segment_size(void)
>  {
>         unsigned int size = swiotlb_max_segment();
> @@ -3101,6 +3116,8 @@ intel_info(const struct drm_i915_private *dev_priv)
>  #define USES_PPGTT(dev_priv)           (i915_modparams.enable_ppgtt)
>  #define USES_FULL_PPGTT(dev_priv)      (i915_modparams.enable_ppgtt >= 2)
>  #define USES_FULL_48BIT_PPGTT(dev_priv)        (i915_modparams.enable_ppgtt == 3)
> +#define HAS_PAGE_SIZES(dev_priv, sizes) \
> +       ((sizes) && (((sizes) & ~(dev_priv)->info.page_sizes)) == 0)

I don't think we ever want to ask if we support a mask of 0, so perhaps

(BUILD_BUG_ON_ZERO(!sizes) ?: (sizes) & ~(dev_priv)->info.page_sizes) == 0)

>  void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
> -                                struct sg_table *pages)
> +                                struct sg_table *pages,
> +                                unsigned int sg_mask)
>  {
> +       struct drm_i915_private *i915 = to_i915(obj->base.dev);
> +       unsigned long supported_page_sizes = INTEL_INFO(i915)->page_sizes;
> +       int i;
> +
>         lockdep_assert_held(&obj->mm.lock);
>  
>         obj->mm.get_page.sg_pos = pages->sgl;
> @@ -2475,6 +2488,25 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
>                 __i915_gem_object_pin_pages(obj);
>                 obj->mm.quirked = true;
>         }
> +
> +       GEM_BUG_ON(!sg_mask);
> +       obj->mm.page_sizes.phys = sg_mask;
> +
> +       /*
> +        * Calculate the supported page-sizes which fit into the given sg_mask.
> +        * This will give us the page-sizes which we may be able to use
> +        * opportunistically when later inserting into the GTT. For example if
> +        * phys=2G, then in theory we should be able to use 1G, 2M, 64K or 4K
> +        * pages, although in practice this will depend on a number of other
> +        * factors.
> +        */
> +       obj->mm.page_sizes.sg = 0;
> +       for_each_set_bit(i, &supported_page_sizes, BITS_PER_LONG) {

s/BITS_PER_LONG/ilog2(MAX_PAGE_SIZE) + 1/ ?

BITS_PER_LONG is definitely inconsistent as the code v is using 0u and
not 0ul :)

> +               if (obj->mm.page_sizes.phys & ~0u << i)
> +                       obj->mm.page_sizes.sg |= BIT(i);
> +       }

Ok, couldn't see anything but I'm going to run it before committing
myself this time! ;)
-Chris