drm/i915/skl: Tune IZ hashing when subslices are unbalanced

When one EU is disabled in a particular subslice, we can tune how the
work is spread between subslices to improve EU utilization.

v2: - Use a bitfield to record which subslice(s) has(have) 7 EUs. That
      will also make the machinery work if several sublices have 7 EUs.
      (Jeff Mcgee)
    - Only apply the different hashing algorithm if the slice is
      effectively unbalanced by checking there's a single subslice with
      7 EUs. (Jeff Mcgee)

v3: Fix typo in comment (Jeff Mcgee)

Issue: VIZ-3845
Cc: Jeff Mcgee <jeff.mcgee@intel.com>
Reviewed-by: Jeff Mcgee <jeff.mcgee@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 61d41abde2e9..4280d0b292da 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -700,6 +700,8 @@ struct intel_device_info {
         u8 subslice_per_slice;
         u8 eu_total;
         u8 eu_per_subslice;
+        /* For each slice, which subslice(s) has(have) 7 EUs (bitfield)? */
+        u8 subslice_7eu[3];
         u8 has_slice_pg:1;
         u8 has_subslice_pg:1;
         u8 has_eu_pg:1;