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| author | Thomas Hellström <thomas.hellstrom@linux.intel.com> | 2021-06-02 11:38:10 +0300 |
|---|---|---|
| committer | Thomas Hellström <thomas.hellstrom@linux.intel.com> | 2021-06-07 17:07:08 +0300 |
| commit | 3bf3710e3718a5aebdf465343bc1125b6e8cca96 (patch) | |
| tree | fdce250a03876dd8202f69c12c2f22b630f73ab4 /include/drm/ttm/ttm_tt.h | |
| parent | c43f2f9842347630f2ebfab05c9972e58b7df9d5 (diff) | |
| download | linux-3bf3710e3718a5aebdf465343bc1125b6e8cca96.tar.xz | |
drm/ttm: Add a generic TTM memcpy move for page-based iomem
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
Diffstat (limited to 'include/drm/ttm/ttm_tt.h')
| -rw-r--r-- | include/drm/ttm/ttm_tt.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h index 134d09ef7766..3102059db726 100644 --- a/include/drm/ttm/ttm_tt.h +++ b/include/drm/ttm/ttm_tt.h @@ -29,6 +29,7 @@ #include <linux/types.h> #include <drm/ttm/ttm_caching.h> +#include <drm/ttm/ttm_kmap_iter.h> struct ttm_bo_device; struct ttm_tt; @@ -69,6 +70,18 @@ struct ttm_tt { enum ttm_caching caching; }; +/** + * struct ttm_kmap_iter_tt - Specialization of a mappig iterator for a tt. + * @base: Embedded struct ttm_kmap_iter providing the usage interface + * @tt: Cached struct ttm_tt. + * @prot: Cached page protection for mapping. + */ +struct ttm_kmap_iter_tt { + struct ttm_kmap_iter base; + struct ttm_tt *tt; + pgprot_t prot; +}; + static inline bool ttm_tt_is_populated(struct ttm_tt *tt) { return tt->page_flags & TTM_PAGE_FLAG_PRIV_POPULATED; @@ -159,6 +172,9 @@ void ttm_tt_unpopulate(struct ttm_device *bdev, struct ttm_tt *ttm); void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages); +struct ttm_kmap_iter *ttm_kmap_iter_tt_init(struct ttm_kmap_iter_tt *iter_tt, + struct ttm_tt *tt); + #if IS_ENABLED(CONFIG_AGP) #include <linux/agp_backend.h> |