Message-ID: <1b0b1ba2-8539-29c0-588e-948a95c79e5a@suse.de>
Date:   Tue, 12 Apr 2022 20:16:41 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Karol Herbst <kherbst@...hat.com>, linux-kernel@...r.kernel.org
Cc:     Lucas De Marchi <lucas.demarchi@...el.com>,
        dri-devel@...ts.freedesktop.org,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Subject: Re: [PATCH] dma-buf-map: remove renamed header file



Am 11.04.22 um 15:44 schrieb Karol Herbst:
> commit 7938f4218168 ("dma-buf-map: Rename to iosys-map") already renamed
> this file, but it got brought back by a merge.
> 
> Delete it for real this time.
> 
> Fixes: 30424ebae8df ("Merge tag 'drm-intel-gt-next-2022-02-17' of git://anongit.freedesktop.org/drm/drm-intel into drm-intel-next")
> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Cc: Lucas De Marchi <lucas.demarchi@...el.com>
> Cc: dri-devel@...ts.freedesktop.org
> Signed-off-by: Karol Herbst <kherbst@...hat.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>   include/linux/dma-buf-map.h | 266 ------------------------------------
>   1 file changed, 266 deletions(-)
>   delete mode 100644 include/linux/dma-buf-map.h
> 
> diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
> deleted file mode 100644
> index 19fa0b5ae5ec..000000000000
> --- a/include/linux/dma-buf-map.h
> +++ /dev/null
> @@ -1,266 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0-only */
> -/*
> - * Pointer to dma-buf-mapped memory, plus helpers.
> - */
> -
> -#ifndef __DMA_BUF_MAP_H__
> -#define __DMA_BUF_MAP_H__
> -
> -#include <linux/io.h>
> -#include <linux/string.h>
> -
> -/**
> - * DOC: overview
> - *
> - * Calling dma-buf's vmap operation returns a pointer to the buffer's memory.
> - * Depending on the location of the buffer, users may have to access it with
> - * I/O operations or memory load/store operations. For example, copying to
> - * system memory could be done with memcpy(), copying to I/O memory would be
> - * done with memcpy_toio().
> - *
> - * .. code-block:: c
> - *
> - *	void *vaddr = ...; // pointer to system memory
> - *	memcpy(vaddr, src, len);
> - *
> - *	void *vaddr_iomem = ...; // pointer to I/O memory
> - *	memcpy_toio(vaddr, _iomem, src, len);
> - *
> - * When using dma-buf's vmap operation, the returned pointer is encoded as
> - * :c:type:`struct dma_buf_map <dma_buf_map>`.
> - * :c:type:`struct dma_buf_map <dma_buf_map>` stores the buffer's address in
> - * system or I/O memory and a flag that signals the required method of
> - * accessing the buffer. Use the returned instance and the helper functions
> - * to access the buffer's memory in the correct way.
> - *
> - * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
> - * actually independent from the dma-buf infrastructure. When sharing buffers
> - * among devices, drivers have to know the location of the memory to access
> - * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
> - * solves this problem for dma-buf and its users. If other drivers or
> - * sub-systems require similar functionality, the type could be generalized
> - * and moved to a more prominent header file.
> - *
> - * Open-coding access to :c:type:`struct dma_buf_map <dma_buf_map>` is
> - * considered bad style. Rather then accessing its fields directly, use one
> - * of the provided helper functions, or implement your own. For example,
> - * instances of :c:type:`struct dma_buf_map <dma_buf_map>` can be initialized
> - * statically with DMA_BUF_MAP_INIT_VADDR(), or at runtime with
> - * dma_buf_map_set_vaddr(). These helpers will set an address in system memory.
> - *
> - * .. code-block:: c
> - *
> - *	struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(0xdeadbeaf);
> - *
> - *	dma_buf_map_set_vaddr(&map, 0xdeadbeaf);
> - *
> - * To set an address in I/O memory, use dma_buf_map_set_vaddr_iomem().
> - *
> - * .. code-block:: c
> - *
> - *	dma_buf_map_set_vaddr_iomem(&map, 0xdeadbeaf);
> - *
> - * Instances of struct dma_buf_map do not have to be cleaned up, but
> - * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
> - * always refer to system memory.
> - *
> - * .. code-block:: c
> - *
> - *	dma_buf_map_clear(&map);
> - *
> - * Test if a mapping is valid with either dma_buf_map_is_set() or
> - * dma_buf_map_is_null().
> - *
> - * .. code-block:: c
> - *
> - *	if (dma_buf_map_is_set(&map) != dma_buf_map_is_null(&map))
> - *		// always true
> - *
> - * Instances of :c:type:`struct dma_buf_map <dma_buf_map>` can be compared
> - * for equality with dma_buf_map_is_equal(). Mappings the point to different
> - * memory spaces, system or I/O, are never equal. That's even true if both
> - * spaces are located in the same address space, both mappings contain the
> - * same address value, or both mappings refer to NULL.
> - *
> - * .. code-block:: c
> - *
> - *	struct dma_buf_map sys_map; // refers to system memory
> - *	struct dma_buf_map io_map; // refers to I/O memory
> - *
> - *	if (dma_buf_map_is_equal(&sys_map, &io_map))
> - *		// always false
> - *
> - * A set up instance of struct dma_buf_map can be used to access or manipulate
> - * the buffer memory. Depending on the location of the memory, the provided
> - * helpers will pick the correct operations. Data can be copied into the memory
> - * with dma_buf_map_memcpy_to(). The address can be manipulated with
> - * dma_buf_map_incr().
> - *
> - * .. code-block:: c
> - *
> - *	const void *src = ...; // source buffer
> - *	size_t len = ...; // length of src
> - *
> - *	dma_buf_map_memcpy_to(&map, src, len);
> - *	dma_buf_map_incr(&map, len); // go to first byte after the memcpy
> - */
> -
> -/**
> - * struct dma_buf_map - Pointer to vmap'ed dma-buf memory.
> - * @vaddr_iomem:	The buffer's address if in I/O memory
> - * @vaddr:		The buffer's address if in system memory
> - * @is_iomem:		True if the dma-buf memory is located in I/O
> - *			memory, or false otherwise.
> - */
> -struct dma_buf_map {
> -	union {
> -		void __iomem *vaddr_iomem;
> -		void *vaddr;
> -	};
> -	bool is_iomem;
> -};
> -
> -/**
> - * DMA_BUF_MAP_INIT_VADDR - Initializes struct dma_buf_map to an address in system memory
> - * @vaddr_:	A system-memory address
> - */
> -#define DMA_BUF_MAP_INIT_VADDR(vaddr_) \
> -	{ \
> -		.vaddr = (vaddr_), \
> -		.is_iomem = false, \
> -	}
> -
> -/**
> - * dma_buf_map_set_vaddr - Sets a dma-buf mapping structure to an address in system memory
> - * @map:	The dma-buf mapping structure
> - * @vaddr:	A system-memory address
> - *
> - * Sets the address and clears the I/O-memory flag.
> - */
> -static inline void dma_buf_map_set_vaddr(struct dma_buf_map *map, void *vaddr)
> -{
> -	map->vaddr = vaddr;
> -	map->is_iomem = false;
> -}
> -
> -/**
> - * dma_buf_map_set_vaddr_iomem - Sets a dma-buf mapping structure to an address in I/O memory
> - * @map:		The dma-buf mapping structure
> - * @vaddr_iomem:	An I/O-memory address
> - *
> - * Sets the address and the I/O-memory flag.
> - */
> -static inline void dma_buf_map_set_vaddr_iomem(struct dma_buf_map *map,
> -					       void __iomem *vaddr_iomem)
> -{
> -	map->vaddr_iomem = vaddr_iomem;
> -	map->is_iomem = true;
> -}
> -
> -/**
> - * dma_buf_map_is_equal - Compares two dma-buf mapping structures for equality
> - * @lhs:	The dma-buf mapping structure
> - * @rhs:	A dma-buf mapping structure to compare with
> - *
> - * Two dma-buf mapping structures are equal if they both refer to the same type of memory
> - * and to the same address within that memory.
> - *
> - * Returns:
> - * True is both structures are equal, or false otherwise.
> - */
> -static inline bool dma_buf_map_is_equal(const struct dma_buf_map *lhs,
> -					const struct dma_buf_map *rhs)
> -{
> -	if (lhs->is_iomem != rhs->is_iomem)
> -		return false;
> -	else if (lhs->is_iomem)
> -		return lhs->vaddr_iomem == rhs->vaddr_iomem;
> -	else
> -		return lhs->vaddr == rhs->vaddr;
> -}
> -
> -/**
> - * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL
> - * @map:	The dma-buf mapping structure
> - *
> - * Depending on the state of struct dma_buf_map.is_iomem, tests if the
> - * mapping is NULL.
> - *
> - * Returns:
> - * True if the mapping is NULL, or false otherwise.
> - */
> -static inline bool dma_buf_map_is_null(const struct dma_buf_map *map)
> -{
> -	if (map->is_iomem)
> -		return !map->vaddr_iomem;
> -	return !map->vaddr;
> -}
> -
> -/**
> - * dma_buf_map_is_set - Tests is the dma-buf mapping has been set
> - * @map:	The dma-buf mapping structure
> - *
> - * Depending on the state of struct dma_buf_map.is_iomem, tests if the
> - * mapping has been set.
> - *
> - * Returns:
> - * True if the mapping is been set, or false otherwise.
> - */
> -static inline bool dma_buf_map_is_set(const struct dma_buf_map *map)
> -{
> -	return !dma_buf_map_is_null(map);
> -}
> -
> -/**
> - * dma_buf_map_clear - Clears a dma-buf mapping structure
> - * @map:	The dma-buf mapping structure
> - *
> - * Clears all fields to zero; including struct dma_buf_map.is_iomem. So
> - * mapping structures that were set to point to I/O memory are reset for
> - * system memory. Pointers are cleared to NULL. This is the default.
> - */
> -static inline void dma_buf_map_clear(struct dma_buf_map *map)
> -{
> -	if (map->is_iomem) {
> -		map->vaddr_iomem = NULL;
> -		map->is_iomem = false;
> -	} else {
> -		map->vaddr = NULL;
> -	}
> -}
> -
> -/**
> - * dma_buf_map_memcpy_to - Memcpy into dma-buf mapping
> - * @dst:	The dma-buf mapping structure
> - * @src:	The source buffer
> - * @len:	The number of byte in src
> - *
> - * Copies data into a dma-buf mapping. The source buffer is in system
> - * memory. Depending on the buffer's location, the helper picks the correct
> - * method of accessing the memory.
> - */
> -static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *src, size_t len)
> -{
> -	if (dst->is_iomem)
> -		memcpy_toio(dst->vaddr_iomem, src, len);
> -	else
> -		memcpy(dst->vaddr, src, len);
> -}
> -
> -/**
> - * dma_buf_map_incr - Increments the address stored in a dma-buf mapping
> - * @map:	The dma-buf mapping structure
> - * @incr:	The number of bytes to increment
> - *
> - * Increments the address stored in a dma-buf mapping. Depending on the
> - * buffer's location, the correct value will be updated.
> - */
> -static inline void dma_buf_map_incr(struct dma_buf_map *map, size_t incr)
> -{
> -	if (map->is_iomem)
> -		map->vaddr_iomem += incr;
> -	else
> -		map->vaddr += incr;
> -}
> -
> -#endif /* __DMA_BUF_MAP_H__ */

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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