Re: [PATCH v7 2/3] drm/i915/gt: Do not generate the command streamer for all the CCS

Hi Matt,

...

• /*

• * Do not create the command streamer for CCS slices beyond the first.
  

• * All the workload submitted to the first engine will be shared among
  

• * all the slices.
  

• *
  

• * Once the user will be allowed to customize the CCS mode, then this
  

• * check needs to be removed.
  

• */
  

• if (IS_DG2(gt->i915)) {

• intel_engine_mask_t first_ccs = BIT((CCS0 + __ffs(CCS_MASK(gt))));
  

• intel_engine_mask_t all_ccs = CCS_MASK(gt) << CCS0;
  

• info->engine_mask &= ~(all_ccs &= ~first_ccs);
  

Shouldn't the second "&=" just be an "&" since there's no need to modify the all_ccs variable that never gets used again?

yes, that's a leftover from me trying different ways of removing all the non first CCS engines.

In fact since this is DG2-specific, it seems like it might be more intuitive to just write the whole thing more directly as

    if (IS_DG2(gt->i915)) {
            int first_ccs = __ffs(CCS_MASK(gt));

            info->engine_mask &= ~GENMASK(CCS3, CCS0);
            info->engine_mask |= BIT(_CCS(first_ccs));
    }

yes, looks a bit simpler. Will use this way.

But up to you; if you just want to remove the unnecessary "=" that's fine too. Either way,

    Reviewed-by: Matt Roper <matthew.d.roper@intel.com>

Thanks!

Andi