forked from Minki/linux
b7e32bef4a
Reading out of write-combining mapped memory is typically very slow since the CPU doesn't prefetch. However some archs have special instructions to do this. So add a best-effort memcpy_from_wc taking dma-buf-map pointer arguments that attempts to use a fast prefetching memcpy and otherwise falls back to ordinary memcopies, taking the iomem tagging into account. The code is largely copied from i915_memcpy_from_wc. Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Christian König <christian.koenig@amd.com> Suggested-by: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Daniel Vetter <daniel@ffwll.ch> Link: https://lore.kernel.org/r/20210602083818.241793-5-thomas.hellstrom@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-5-thomas.hellstrom@linux.intel.com
81 lines
3.0 KiB
C
81 lines
3.0 KiB
C
/**************************************************************************
|
|
*
|
|
* Copyright 2009 Red Hat Inc.
|
|
* All Rights Reserved.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a
|
|
* copy of this software and associated documentation files (the
|
|
* "Software"), to deal in the Software without restriction, including
|
|
* without limitation the rights to use, copy, modify, merge, publish,
|
|
* distribute, sub license, and/or sell copies of the Software, and to
|
|
* permit persons to whom the Software is furnished to do so, subject to
|
|
* the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice (including the
|
|
* next paragraph) shall be included in all copies or substantial portions
|
|
* of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
|
|
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
|
|
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
|
|
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
|
|
* USE OR OTHER DEALINGS IN THE SOFTWARE.
|
|
*
|
|
*
|
|
**************************************************************************/
|
|
/*
|
|
* Authors:
|
|
* Dave Airlie <airlied@redhat.com>
|
|
*/
|
|
|
|
#ifndef _DRM_CACHE_H_
|
|
#define _DRM_CACHE_H_
|
|
|
|
#include <linux/scatterlist.h>
|
|
|
|
struct dma_buf_map;
|
|
|
|
void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
|
|
void drm_clflush_sg(struct sg_table *st);
|
|
void drm_clflush_virt_range(void *addr, unsigned long length);
|
|
bool drm_need_swiotlb(int dma_bits);
|
|
|
|
|
|
static inline bool drm_arch_can_wc_memory(void)
|
|
{
|
|
#if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
|
|
return false;
|
|
#elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON64)
|
|
return false;
|
|
#elif defined(CONFIG_ARM) || defined(CONFIG_ARM64)
|
|
/*
|
|
* The DRM driver stack is designed to work with cache coherent devices
|
|
* only, but permits an optimization to be enabled in some cases, where
|
|
* for some buffers, both the CPU and the GPU use uncached mappings,
|
|
* removing the need for DMA snooping and allocation in the CPU caches.
|
|
*
|
|
* The use of uncached GPU mappings relies on the correct implementation
|
|
* of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU
|
|
* will use cached mappings nonetheless. On x86 platforms, this does not
|
|
* seem to matter, as uncached CPU mappings will snoop the caches in any
|
|
* case. However, on ARM and arm64, enabling this optimization on a
|
|
* platform where NoSnoop is ignored results in loss of coherency, which
|
|
* breaks correct operation of the device. Since we have no way of
|
|
* detecting whether NoSnoop works or not, just disable this
|
|
* optimization entirely for ARM and arm64.
|
|
*/
|
|
return false;
|
|
#else
|
|
return true;
|
|
#endif
|
|
}
|
|
|
|
void drm_memcpy_init_early(void);
|
|
|
|
void drm_memcpy_from_wc(struct dma_buf_map *dst,
|
|
const struct dma_buf_map *src,
|
|
unsigned long len);
|
|
#endif
|