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The internal ttm_bo_util memcpy uses ioremap functionality, and while it probably might be possible to use it for copying in- and out of sglist represented io memory, using io_mem_reserve() / io_mem_free() callbacks, that would cause problems with fault(). Instead, implement a method mapping page-by-page using kmap_local() semantics. As an additional benefit we then avoid the occasional global TLB flushes of ioremap() and consuming ioremap space, elimination of a critical point of failure and with a slight change of semantics we could also push the memcpy out async for testing and async driver development purposes. A special linear iomem iterator is introduced internally to mimic the old ioremap behaviour for code-paths that can't immediately be ported over. This adds to the code size and should be considered a temporary solution. Looking at the code we have a lot of checks for iomap tagged pointers. Ideally we should extend the core memremap functions to also accept uncached memory and kmap_local functionality. Then we could strip a lot of code. Cc: Christian König <christian.koenig@amd.com> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://lore.kernel.org/r/20210602083818.241793-4-thomas.hellstrom@linux.intel.com
39 lines
1.4 KiB
C
39 lines
1.4 KiB
C
/*
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* Copyright 2020 Advanced Micro Devices, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* Authors: Christian König
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*/
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#ifndef _TTM_CACHING_H_
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#define _TTM_CACHING_H_
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#define TTM_NUM_CACHING_TYPES 3
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enum ttm_caching {
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ttm_uncached,
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ttm_write_combined,
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ttm_cached
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};
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pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp);
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#endif
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