From 3bf3710e3718a5aebdf465343bc1125b6e8cca96 Mon Sep 17 00:00:00 2001 From: Thomas Hellström <thomas.hellstrom@linux.intel.com> Date: Wed, 2 Jun 2021 10:38:10 +0200 Subject: drm/ttm: Add a generic TTM memcpy move for page-based iomem MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- include/drm/ttm/ttm_kmap_iter.h | 61 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 include/drm/ttm/ttm_kmap_iter.h (limited to 'include/drm/ttm/ttm_kmap_iter.h') diff --git a/include/drm/ttm/ttm_kmap_iter.h b/include/drm/ttm/ttm_kmap_iter.h new file mode 100644 index 000000000000..8bb00fd39d6c --- /dev/null +++ b/include/drm/ttm/ttm_kmap_iter.h @@ -0,0 +1,61 @@ +/* SPDX-License-Identifier: MIT */ +/* + * Copyright © 2021 Intel Corporation + */ +#ifndef __TTM_KMAP_ITER_H__ +#define __TTM_KMAP_ITER_H__ + +#include <linux/types.h> + +struct ttm_kmap_iter; +struct dma_buf_map; + +/** + * struct ttm_kmap_iter_ops - Ops structure for a struct + * ttm_kmap_iter. + * @maps_tt: Whether the iterator maps TT memory directly, as opposed + * mapping a TT through an aperture. Both these modes have + * struct ttm_resource_manager::use_tt set, but the latter typically + * returns is_iomem == true from ttm_mem_io_reserve. + */ +struct ttm_kmap_iter_ops { + /** + * kmap_local() - Map a PAGE_SIZE part of the resource using + * kmap_local semantics. + * @res_iter: Pointer to the struct ttm_kmap_iter representing + * the resource. + * @dmap: The struct dma_buf_map holding the virtual address after + * the operation. + * @i: The location within the resource to map. PAGE_SIZE granularity. + */ + void (*map_local)(struct ttm_kmap_iter *res_iter, + struct dma_buf_map *dmap, pgoff_t i); + /** + * unmap_local() - Unmap a PAGE_SIZE part of the resource previously + * mapped using kmap_local. + * @res_iter: Pointer to the struct ttm_kmap_iter representing + * the resource. + * @dmap: The struct dma_buf_map holding the virtual address after + * the operation. + */ + void (*unmap_local)(struct ttm_kmap_iter *res_iter, + struct dma_buf_map *dmap); + bool maps_tt; +}; + +/** + * struct ttm_kmap_iter - Iterator for kmap_local type operations on a + * resource. + * @ops: Pointer to the operations struct. + * + * This struct is intended to be embedded in a resource-specific specialization + * implementing operations for the resource. + * + * Nothing stops us from extending the operations to vmap, vmap_pfn etc, + * replacing some or parts of the ttm_bo_util. cpu-map functionality. + */ +struct ttm_kmap_iter { + const struct ttm_kmap_iter_ops *ops; +}; + +#endif /* __TTM_KMAP_ITER_H__ */ -- cgit v1.2.3