1. 15 2月, 2017 39 次提交
  2. 14 2月, 2017 1 次提交
    • T
      drm/i915: Emit to ringbuffer directly · 73dec95e
      Tvrtko Ursulin 提交于
      This removes the usage of intel_ring_emit in favour of
      directly writing to the ring buffer.
      
      intel_ring_emit was preventing the compiler for optimising
      fetch and increment of the current ring buffer pointer and
      therefore generating very verbose code for every write.
      
      It had no useful purpose since all ringbuffer operations
      are started and ended with intel_ring_begin and
      intel_ring_advance respectively, with no bail out in the
      middle possible, so it is fine to increment the tail in
      intel_ring_begin and let the code manage the pointer
      itself.
      
      Useless instruction removal amounts to approximately
      two and half kilobytes of saved text on my build.
      
      Not sure if this has any measurable performance
      implications but executing a ton of useless instructions
      on fast paths cannot be good.
      
      v2:
       * Change return from intel_ring_begin to error pointer by
         popular demand.
       * Move tail increment to intel_ring_advance to enable some
         error checking.
      
      v3:
       * Move tail advance back into intel_ring_begin.
       * Rebase and tidy.
      
      v4:
       * Complete rebase after a few months since v3.
      
      v5:
       * Remove unecessary cast and fix !debug compile. (Chris Wilson)
      
      v6:
       * Make intel_ring_offset take request as well.
       * Fix recording of request postfix plus a sprinkle of asserts.
         (Chris Wilson)
      
      v7:
       * Use intel_ring_offset to get the postfix. (Chris Wilson)
       * Convert GVT code as well.
      
      v8:
       * Rename *out++ to *cs++.
      
      v9:
       * Fix GVT out to cs conversion in GVT.
      
      v10:
       * Rebase for new intel_ring_begin in selftests.
      Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
      Cc: Zhi Wang <zhi.a.wang@intel.com>
      Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
      Acked-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
      Link: http://patchwork.freedesktop.org/patch/msgid/20170214113242.29241-1-tvrtko.ursulin@linux.intel.com
      73dec95e