1*4882a593Smuzhiyun /**************************************************************************
2*4882a593Smuzhiyun *
3*4882a593Smuzhiyun * Copyright 2009 Red Hat Inc.
4*4882a593Smuzhiyun * All Rights Reserved.
5*4882a593Smuzhiyun *
6*4882a593Smuzhiyun * Permission is hereby granted, free of charge, to any person obtaining a
7*4882a593Smuzhiyun * copy of this software and associated documentation files (the
8*4882a593Smuzhiyun * "Software"), to deal in the Software without restriction, including
9*4882a593Smuzhiyun * without limitation the rights to use, copy, modify, merge, publish,
10*4882a593Smuzhiyun * distribute, sub license, and/or sell copies of the Software, and to
11*4882a593Smuzhiyun * permit persons to whom the Software is furnished to do so, subject to
12*4882a593Smuzhiyun * the following conditions:
13*4882a593Smuzhiyun *
14*4882a593Smuzhiyun * The above copyright notice and this permission notice (including the
15*4882a593Smuzhiyun * next paragraph) shall be included in all copies or substantial portions
16*4882a593Smuzhiyun * of the Software.
17*4882a593Smuzhiyun *
18*4882a593Smuzhiyun * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19*4882a593Smuzhiyun * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20*4882a593Smuzhiyun * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21*4882a593Smuzhiyun * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22*4882a593Smuzhiyun * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23*4882a593Smuzhiyun * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24*4882a593Smuzhiyun * USE OR OTHER DEALINGS IN THE SOFTWARE.
25*4882a593Smuzhiyun *
26*4882a593Smuzhiyun *
27*4882a593Smuzhiyun **************************************************************************/
28*4882a593Smuzhiyun /*
29*4882a593Smuzhiyun * Authors:
30*4882a593Smuzhiyun * Dave Airlie <airlied@redhat.com>
31*4882a593Smuzhiyun */
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun #ifndef _DRM_CACHE_H_
34*4882a593Smuzhiyun #define _DRM_CACHE_H_
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun #include <linux/scatterlist.h>
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
39*4882a593Smuzhiyun void drm_clflush_sg(struct sg_table *st);
40*4882a593Smuzhiyun void drm_clflush_virt_range(void *addr, unsigned long length);
41*4882a593Smuzhiyun bool drm_need_swiotlb(int dma_bits);
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun
drm_arch_can_wc_memory(void)44*4882a593Smuzhiyun static inline bool drm_arch_can_wc_memory(void)
45*4882a593Smuzhiyun {
46*4882a593Smuzhiyun #if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
47*4882a593Smuzhiyun return false;
48*4882a593Smuzhiyun #elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON64)
49*4882a593Smuzhiyun return false;
50*4882a593Smuzhiyun #elif defined(CONFIG_ARM) || defined(CONFIG_ARM64)
51*4882a593Smuzhiyun /*
52*4882a593Smuzhiyun * The DRM driver stack is designed to work with cache coherent devices
53*4882a593Smuzhiyun * only, but permits an optimization to be enabled in some cases, where
54*4882a593Smuzhiyun * for some buffers, both the CPU and the GPU use uncached mappings,
55*4882a593Smuzhiyun * removing the need for DMA snooping and allocation in the CPU caches.
56*4882a593Smuzhiyun *
57*4882a593Smuzhiyun * The use of uncached GPU mappings relies on the correct implementation
58*4882a593Smuzhiyun * of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU
59*4882a593Smuzhiyun * will use cached mappings nonetheless. On x86 platforms, this does not
60*4882a593Smuzhiyun * seem to matter, as uncached CPU mappings will snoop the caches in any
61*4882a593Smuzhiyun * case. However, on ARM and arm64, enabling this optimization on a
62*4882a593Smuzhiyun * platform where NoSnoop is ignored results in loss of coherency, which
63*4882a593Smuzhiyun * breaks correct operation of the device. Since we have no way of
64*4882a593Smuzhiyun * detecting whether NoSnoop works or not, just disable this
65*4882a593Smuzhiyun * optimization entirely for ARM and arm64.
66*4882a593Smuzhiyun */
67*4882a593Smuzhiyun return false;
68*4882a593Smuzhiyun #else
69*4882a593Smuzhiyun return true;
70*4882a593Smuzhiyun #endif
71*4882a593Smuzhiyun }
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun #endif
74