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Commit 46b86332 authored by Chris Wilson's avatar Chris Wilson
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drm/i915: Prefer memset64() when filling the iomap 



As the ringbuffer may exist inside stolen memory, our access to it may
be via the GTT iomap. This implies we may only have WC access for which
the conventional memset() substitution of rep stos performs very badly,
so switch to the rep mov[dq] variants when available.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180319123528.28249-1-chris@chris-wilson.co.uk
parent feb06c15

drivers/gpu/drm/i915/intel_ringbuffer.c

+4 −3
Original line number Diff line number Diff line
@@ -1693,17 +1693,18 @@ u32 *intel_ring_begin(struct i915_request *rq, unsigned int num_dwords) 
		need_wrap &= ~1;

		GEM_BUG_ON(need_wrap > ring->space);

		GEM_BUG_ON(ring->emit + need_wrap > ring->size);

		GEM_BUG_ON(!IS_ALIGNED(need_wrap, sizeof(u64)));



		/* Fill the tail with MI_NOOP */

		memset(ring->vaddr + ring->emit, 0, need_wrap);

		ring->emit = 0;

		memset64(ring->vaddr + ring->emit, 0, need_wrap / sizeof(u64));

		ring->space -= need_wrap;

		ring->emit = 0;

	}



	GEM_BUG_ON(ring->emit > ring->size - bytes);

	GEM_BUG_ON(ring->space < bytes);

	cs = ring->vaddr + ring->emit;

	GEM_DEBUG_EXEC(memset(cs, POISON_INUSE, bytes));

	GEM_DEBUG_EXEC(memset32(cs, POISON_INUSE, bytes / sizeof(*cs)));

	ring->emit += bytes;

	ring->space -= bytes;