u32 intel_calculate_mcr_s_ss_select(struct drm_i915_private *dev_priv)
{
const struct sseu_dev_info *sseu = &RUNTIME_INFO(dev_priv)->sseu;
+ unsigned int slice = fls(sseu->slice_mask) - 1;
+ unsigned int subslice;
u32 mcr_s_ss_select;
- u32 slice = fls(sseu->slice_mask);
- u32 subslice = fls(sseu->subslice_mask[slice]);
+
+ GEM_BUG_ON(slice >= ARRAY_SIZE(sseu->subslice_mask));
+ subslice = fls(sseu->subslice_mask[slice]);
+ GEM_BUG_ON(!subslice);
+ subslice--;
if (IS_GEN(dev_priv, 10))
mcr_s_ss_select = GEN8_MCR_SLICE(slice) |