Quoting Chris Wilson (2019-07-07 22:00:18)
> The radix levels of each page directory are easily determined so replace
> the numerous hardcoded constants with precomputed derived constants.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 39 +++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 2fc60e8acd9a..271305705c1c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -868,6 +868,45 @@ static int gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
> return 0;
> }
>
> +/* Index shifts into the pagetable are offset by GEN8_PTE_SHIFT [12] */
> +#define gen8_pd_shift(lvl) ((lvl) * ilog2(I915_PDES))
> +#define gen8_pd_index(i, lvl) i915_pde_index((i), gen8_pd_shift(lvl))
> +#define __gen8_pte_shift(lvl) (GEN8_PTE_SHIFT + gen8_pd_shift(lvl))
> +#define __gen8_pte_index(a, lvl) i915_pde_index((a), __gen8_pte_shift(lvl))
> +
> +static inline unsigned int
> +gen8_pd_range(u64 addr, u64 end, int lvl, unsigned int *idx)
> +{
> + const int shift = gen8_pd_shift(lvl);
> + const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
> +
> + GEM_BUG_ON(addr >= end);
> + end += ~mask >> gen8_pd_shift(1);
> +
> + *idx = i915_pde_index(addr, shift);
> + if ((addr ^ end) & mask)
> + return I915_PDES - *idx;
> + else
> + return i915_pde_index(end, shift) - *idx;
> +}
> +
> +static inline bool gen8_pd_subsumes(u64 addr, u64 end, int lvl)
> +{
> + const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
> +
> + GEM_BUG_ON(addr >= end);
> + return (addr ^ end) & mask && (addr & ~mask) == 0;
> +}
> +
> +static inline unsigned int gen8_pt_count(u64 addr, u64 end)
> +{
> + GEM_BUG_ON(addr >= end);
> + if ((addr ^ end) & ~I915_PDE_MASK)
> + return I915_PDES - (addr & I915_PDE_MASK);
> + else
> + return end - addr;
> +}
So this is the question, do you want these as 512 and 0x1ff?
Or just define gen8_pd_shift(lvl) as ((lvl) * ilog(512))
and work from there. Hmm.
-Chris
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