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The movntqda requires 16-byte alignment for the source pointer. Avoid falling back to clflush if the source pointer is misaligned by doing the doing a small uncached memcpy to fixup the alignments. v2: Turn the unaligned copy into a genuine helper Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191211110437.4082687-5-chris@chris-wilson.co.uk
35 lines
1.2 KiB
C
35 lines
1.2 KiB
C
/* SPDX-License-Identifier: MIT */
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/*
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* Copyright © 2019 Intel Corporation
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*/
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#ifndef __I915_MEMCPY_H__
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#define __I915_MEMCPY_H__
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#include <linux/types.h>
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struct drm_i915_private;
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void i915_memcpy_init_early(struct drm_i915_private *i915);
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bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len);
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void i915_unaligned_memcpy_from_wc(void *dst, void *src, unsigned long len);
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/* The movntdqa instructions used for memcpy-from-wc require 16-byte alignment,
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* as well as SSE4.1 support. i915_memcpy_from_wc() will report if it cannot
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* perform the operation. To check beforehand, pass in the parameters to
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* to i915_can_memcpy_from_wc() - since we only care about the low 4 bits,
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* you only need to pass in the minor offsets, page-aligned pointers are
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* always valid.
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*
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* For just checking for SSE4.1, in the foreknowledge that the future use
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* will be correctly aligned, just use i915_has_memcpy_from_wc().
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*/
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#define i915_can_memcpy_from_wc(dst, src, len) \
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i915_memcpy_from_wc((void *)((unsigned long)(dst) | (unsigned long)(src) | (len)), NULL, 0)
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#define i915_has_memcpy_from_wc() \
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i915_memcpy_from_wc(NULL, NULL, 0)
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#endif /* __I915_MEMCPY_H__ */
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