[Mesa-dev] [PATCH] isl: round format alignment to nearest power of 2

[Ilia Mirkin]

On Fri, Aug 19, 2016 at 7:44 PM, Lionel Landwerlin
<llandwerlin at gmail.com> wrote:
> A few inline asserts in anv assume alignments are power of 2, but with
> formats like R8G8B8 we have odd alignments.
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>  src/intel/isl/isl.c      | 1 +
>  src/intel/isl/isl_priv.h | 6 ++++++
>  2 files changed, 7 insertions(+)
>
> diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
> index 18e95e2..dfe0fc1 100644
> --- a/src/intel/isl/isl.c
> +++ b/src/intel/isl/isl.c
> @@ -1182,6 +1182,7 @@ isl_surf_init_s(const struct isl_device *dev,
>              base_alignment = MAX(base_alignment, fmtl->bpb / 8);
>           }
>        }
> +      base_alignment = isl_round_to_power_of_two(base_alignment);
>     } else {
>        assert(phys_slice0_sa.w % fmtl->bw == 0);
>        const uint32_t total_w_el = phys_slice0_sa.width / fmtl->bw;
> diff --git a/src/intel/isl/isl_priv.h b/src/intel/isl/isl_priv.h
> index 3a7af1a..cc9991c 100644
> --- a/src/intel/isl/isl_priv.h
> +++ b/src/intel/isl/isl_priv.h
> @@ -99,6 +99,12 @@ isl_log2u(uint32_t n)
>  }
>
>  static inline uint32_t
> +isl_round_to_power_of_two(uint32_t value)
> +{
> +   return 1 << isl_log2u(value);

This will round down. Is that desired? (Don't know, just asking... I
kind of assumed you'd want to round up to the nearest power of two,
but perhaps not.)

> +}
> +
> +static inline uint32_t
>  isl_minify(uint32_t n, uint32_t levels)
>  {
>     if (unlikely(n == 0))
> --
> 2.9.3
>
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