[Intel-gfx] [PATCH 07/11] drm/i915: Use subslice stride to set subslices for a given slice

[Chris Wilson]

Quoting Stuart Summers (2019-08-22 19:32:09)
> Add a subslice stride calculation when setting subslices. This
> aligns more closely with the userspace expectation of the subslice
> mask structure.
> 
> v2: Use local variable for subslice_mask on HSW and
>     clean up a few other subslice_mask local variable
>     changes
> v3: Add GEM_BUG_ON for ss_stride to prevent array overflow (Chris)
>     Split main set function and refactors in intel_device_info.c
>     into separate patches (Chris)
> v4: Reduce ss_stride size check when setting subslices per slice
>     based on actual expected max stride (Chris)
>     Move that GEM_BUG_ON check for the ss_stride out to the patch
>     which adds the ss_stride
> 
> Signed-off-by: Stuart Summers <stuart.summers at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_sseu.c | 8 ++++++--
>  drivers/gpu/drm/i915/gt/intel_sseu.h | 2 +-
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_sseu.c b/drivers/gpu/drm/i915/gt/intel_sseu.c
> index 3a5db0dbac72..a0d32270248c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_sseu.c
> +++ b/drivers/gpu/drm/i915/gt/intel_sseu.c
> @@ -33,9 +33,13 @@ intel_sseu_subslice_total(const struct sseu_dev_info *sseu)
>  }
>  
>  void intel_sseu_set_subslices(struct sseu_dev_info *sseu, int slice,
> -                             u8 ss_mask)
> +                             u32 ss_mask)
>  {
> -       sseu->subslice_mask[slice] = ss_mask;
> +       int i, offset = slice * sseu->ss_stride;
> +
> +       for (i = 0; i < sseu->ss_stride; i++)
> +               sseu->subslice_mask[offset + i] =
> +                       (ss_mask >> (BITS_PER_BYTE * i)) & 0xff;

Is it not

	memcpy(&sseu->sublice_mask[offset], &ss_mask, sseu->ss_stride);
?
-Chris