From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx124.postini.com [74.125.245.124]) by kanga.kvack.org (Postfix) with SMTP id 2CDED6B004D for ; Tue, 27 Dec 2011 21:27:32 -0500 (EST) Received: by werf1 with SMTP id f1so7744664wer.14 for ; Tue, 27 Dec 2011 18:27:30 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1324891397-10877-2-git-send-email-sumit.semwal@ti.com> References: <1324891397-10877-1-git-send-email-sumit.semwal@ti.com> <1324891397-10877-2-git-send-email-sumit.semwal@ti.com> Date: Wed, 28 Dec 2011 11:27:29 +0900 Message-ID: Subject: Re: [PATCH 1/3] dma-buf: Introduce dma buffer sharing mechanism From: InKi Dae Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Sumit Semwal Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, arnd@arndb.de, airlied@redhat.com, linux@arm.linux.org.uk, jesse.barker@linaro.org, m.szyprowski@samsung.com, rob@ti.com, daniel@ffwll.ch, t.stanislaws@samsung.com, patches@linaro.org, Sumit Semwal 2011/12/26 Sumit Semwal : > This is the first step in defining a dma buffer sharing mechanism. > > A new buffer object dma_buf is added, with operations and API to allow ea= sy > sharing of this buffer object across devices. > > The framework allows: > - creation of a buffer object, its association with a file pointer, and > =A0 associated allocator-defined operations on that buffer. This operatio= n is > =A0 called the 'export' operation. > - different devices to 'attach' themselves to this exported buffer object= , to > =A0facilitate backing storage negotiation, using dma_buf_attach() API. > - the exported buffer object to be shared with the other entity by asking= for > =A0 its 'file-descriptor (fd)', and sharing the fd across. > - a received fd to get the buffer object back, where it can be accessed u= sing > =A0 the associated exporter-defined operations. > - the exporter and user to share the scatterlist associated with this buf= fer > =A0 object using map_dma_buf and unmap_dma_buf operations. > > Atleast one 'attach()' call is required to be made prior to calling the > map_dma_buf() operation. > > Couple of building blocks in map_dma_buf() are added to ease introduction > of sync'ing across exporter and users, and late allocation by the exporte= r. > > For this first version, this framework will work with certain conditions: > - *ONLY* exporter will be allowed to mmap to userspace (outside of this > =A0 framework - mmap is not a buffer object operation), > - currently, *ONLY* users that do not need CPU access to the buffer are > =A0 allowed. > > More details are there in the documentation patch. > > This is based on design suggestions from many people at the mini-summits[= 1], > most notably from Arnd Bergmann , Rob Clark a= nd > Daniel Vetter . > > The implementation is inspired from proof-of-concept patch-set from > Tomasz Stanislawski , who demonstrated buffer s= haring > between two v4l2 devices. [2] > > [1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement > [2]: http://lwn.net/Articles/454389 > > Signed-off-by: Sumit Semwal > Signed-off-by: Sumit Semwal > Reviewed-by: Daniel Vetter > Reviewed-by: Dave Airlie > Reviewed-and-Tested-by: Rob Clark > --- > =A0drivers/base/Kconfig =A0 =A0| =A0 10 ++ > =A0drivers/base/Makefile =A0 | =A0 =A01 + > =A0drivers/base/dma-buf.c =A0| =A0291 +++++++++++++++++++++++++++++++++++= ++++++++++++ > =A0include/linux/dma-buf.h | =A0176 ++++++++++++++++++++++++++++ > =A04 files changed, 478 insertions(+), 0 deletions(-) > =A0create mode 100644 drivers/base/dma-buf.c > =A0create mode 100644 include/linux/dma-buf.h > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index 21cf46f..8a0e87f 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -174,4 +174,14 @@ config SYS_HYPERVISOR > > =A0source "drivers/base/regmap/Kconfig" > > +config DMA_SHARED_BUFFER > + =A0 =A0 =A0 bool "Buffer framework to be shared between drivers" > + =A0 =A0 =A0 default n > + =A0 =A0 =A0 select ANON_INODES > + =A0 =A0 =A0 help > + =A0 =A0 =A0 =A0 This option enables the framework for buffer-sharing be= tween > + =A0 =A0 =A0 =A0 multiple drivers. A buffer is associated with a file us= ing driver > + =A0 =A0 =A0 =A0 APIs extension; the file's descriptor can then be passe= d on to other > + =A0 =A0 =A0 =A0 driver. > + > =A0endmenu > diff --git a/drivers/base/Makefile b/drivers/base/Makefile > index 99a375a..d0df046 100644 > --- a/drivers/base/Makefile > +++ b/drivers/base/Makefile > @@ -8,6 +8,7 @@ obj-$(CONFIG_DEVTMPFS) =A0+=3D devtmpfs.o > =A0obj-y =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0+=3D power/ > =A0obj-$(CONFIG_HAS_DMA) =A0+=3D dma-mapping.o > =A0obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) +=3D dma-coherent.o > +obj-$(CONFIG_DMA_SHARED_BUFFER) +=3D dma-buf.o > =A0obj-$(CONFIG_ISA) =A0 =A0 =A0+=3D isa.o > =A0obj-$(CONFIG_FW_LOADER) =A0 =A0 =A0 =A0+=3D firmware_class.o > =A0obj-$(CONFIG_NUMA) =A0 =A0 +=3D node.o > diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c > new file mode 100644 > index 0000000..e38ad24 > --- /dev/null > +++ b/drivers/base/dma-buf.c > @@ -0,0 +1,291 @@ > +/* > + * Framework for buffer objects that can be shared across devices/subsys= tems. > + * > + * Copyright(C) 2011 Linaro Limited. All rights reserved. > + * Author: Sumit Semwal > + * > + * Many thanks to linaro-mm-sig list, and specially > + * Arnd Bergmann , Rob Clark and > + * Daniel Vetter for their support in creation and > + * refining of this idea. > + * > + * This program is free software; you can redistribute it and/or modify = it > + * under the terms of the GNU General Public License version 2 as publis= hed by > + * the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, but W= ITHOUT > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or > + * FITNESS FOR A PARTICULAR PURPOSE. =A0See the GNU General Public Licen= se for > + * more details. > + * > + * You should have received a copy of the GNU General Public License alo= ng with > + * this program. =A0If not, see . > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +static inline int is_dma_buf_file(struct file *); > + > +static int dma_buf_release(struct inode *inode, struct file *file) > +{ > + =A0 =A0 =A0 struct dma_buf *dmabuf; > + > + =A0 =A0 =A0 if (!is_dma_buf_file(file)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return -EINVAL; > + > + =A0 =A0 =A0 dmabuf =3D file->private_data; > + > + =A0 =A0 =A0 dmabuf->ops->release(dmabuf); > + =A0 =A0 =A0 kfree(dmabuf); > + =A0 =A0 =A0 return 0; > +} > + > +static const struct file_operations dma_buf_fops =3D { > + =A0 =A0 =A0 .release =A0 =A0 =A0 =A0=3D dma_buf_release, > +}; > + > +/* > + * is_dma_buf_file - Check if struct file* is associated with dma_buf > + */ > +static inline int is_dma_buf_file(struct file *file) > +{ > + =A0 =A0 =A0 return file->f_op =3D=3D &dma_buf_fops; > +} > + > +/** > + * dma_buf_export - Creates a new dma_buf, and associates an anon file > + * with this buffer, so it can be exported. > + * Also connect the allocator specific data and ops to the buffer. > + * > + * @priv: =A0 =A0 =A0[in] =A0 =A0Attach private data of allocator to thi= s buffer > + * @ops: =A0 =A0 =A0 [in] =A0 =A0Attach allocator-defined dma buf ops to= the new buffer. > + * @size: =A0 =A0 =A0[in] =A0 =A0Size of the buffer > + * @flags: =A0 =A0 [in] =A0 =A0mode flags for the file. > + * > + * Returns, on success, a newly created dma_buf object, which wraps the > + * supplied private data and operations for dma_buf_ops. On either missi= ng > + * ops, or error in allocating struct dma_buf, will return negative erro= r. > + * > + */ > +struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 size_t size= , int flags) > +{ > + =A0 =A0 =A0 struct dma_buf *dmabuf; > + =A0 =A0 =A0 struct file *file; > + > + =A0 =A0 =A0 if (WARN_ON(!priv || !ops > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 || !ops->map_dma_buf > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 || !ops->unmap_dma_buf > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 || !ops->release)) { > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-EINVAL); > + =A0 =A0 =A0 } > + > + =A0 =A0 =A0 dmabuf =3D kzalloc(sizeof(struct dma_buf), GFP_KERNEL); > + =A0 =A0 =A0 if (dmabuf =3D=3D NULL) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-ENOMEM); > + > + =A0 =A0 =A0 dmabuf->priv =3D priv; > + =A0 =A0 =A0 dmabuf->ops =3D ops; > + =A0 =A0 =A0 dmabuf->size =3D size; > + > + =A0 =A0 =A0 file =3D anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf= , flags); > + > + =A0 =A0 =A0 dmabuf->file =3D file; > + > + =A0 =A0 =A0 mutex_init(&dmabuf->lock); > + =A0 =A0 =A0 INIT_LIST_HEAD(&dmabuf->attachments); > + > + =A0 =A0 =A0 return dmabuf; > +} > +EXPORT_SYMBOL_GPL(dma_buf_export); > + > + > +/** > + * dma_buf_fd - returns a file descriptor for the given dma_buf > + * @dmabuf: =A0 =A0[in] =A0 =A0pointer to dma_buf for which fd is requir= ed. > + * > + * On success, returns an associated 'fd'. Else, returns error. > + */ > +int dma_buf_fd(struct dma_buf *dmabuf) > +{ > + =A0 =A0 =A0 int error, fd; > + > + =A0 =A0 =A0 if (!dmabuf || !dmabuf->file) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return -EINVAL; > + > + =A0 =A0 =A0 error =3D get_unused_fd(); > + =A0 =A0 =A0 if (error < 0) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return error; > + =A0 =A0 =A0 fd =3D error; > + > + =A0 =A0 =A0 fd_install(fd, dmabuf->file); > + > + =A0 =A0 =A0 return fd; > +} > +EXPORT_SYMBOL_GPL(dma_buf_fd); > + > +/** > + * dma_buf_get - returns the dma_buf structure related to an fd > + * @fd: =A0 =A0 =A0 =A0[in] =A0 =A0fd associated with the dma_buf to be = returned > + * > + * On success, returns the dma_buf structure associated with an fd; uses > + * file's refcounting done by fget to increase refcount. returns ERR_PTR > + * otherwise. > + */ > +struct dma_buf *dma_buf_get(int fd) > +{ > + =A0 =A0 =A0 struct file *file; > + > + =A0 =A0 =A0 file =3D fget(fd); > + > + =A0 =A0 =A0 if (!file) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-EBADF); > + > + =A0 =A0 =A0 if (!is_dma_buf_file(file)) { > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 fput(file); > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-EINVAL); > + =A0 =A0 =A0 } > + > + =A0 =A0 =A0 return file->private_data; > +} > +EXPORT_SYMBOL_GPL(dma_buf_get); > + > +/** > + * dma_buf_put - decreases refcount of the buffer > + * @dmabuf: =A0 =A0[in] =A0 =A0buffer to reduce refcount of > + * > + * Uses file's refcounting done implicitly by fput() > + */ > +void dma_buf_put(struct dma_buf *dmabuf) > +{ > + =A0 =A0 =A0 if (WARN_ON(!dmabuf || !dmabuf->file)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return; > + > + =A0 =A0 =A0 fput(dmabuf->file); > +} > +EXPORT_SYMBOL_GPL(dma_buf_put); > + > +/** > + * dma_buf_attach - Add the device to dma_buf's attachments list; option= ally, > + * calls attach() of dma_buf_ops to allow device-specific attach functio= nality > + * @dmabuf: =A0 =A0[in] =A0 =A0buffer to attach device to. > + * @dev: =A0 =A0 =A0 [in] =A0 =A0device to be attached. > + * > + * Returns struct dma_buf_attachment * for this attachment; may return n= egative > + * error codes. > + * > + */ > +struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 struct device *dev) > +{ > + =A0 =A0 =A0 struct dma_buf_attachment *attach; > + =A0 =A0 =A0 int ret; > + > + =A0 =A0 =A0 if (WARN_ON(!dmabuf || !dev || !dmabuf->ops)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-EINVAL); > + > + =A0 =A0 =A0 attach =3D kzalloc(sizeof(struct dma_buf_attachment), GFP_K= ERNEL); > + =A0 =A0 =A0 if (attach =3D=3D NULL) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto err_alloc; > + > + =A0 =A0 =A0 mutex_lock(&dmabuf->lock); > + > + =A0 =A0 =A0 attach->dev =3D dev; > + =A0 =A0 =A0 attach->dmabuf =3D dmabuf; > + =A0 =A0 =A0 if (dmabuf->ops->attach) { > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 ret =3D dmabuf->ops->attach(dmabuf, dev, at= tach); > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (ret) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto err_attach; > + =A0 =A0 =A0 } > + =A0 =A0 =A0 list_add(&attach->node, &dmabuf->attachments); > + > + =A0 =A0 =A0 mutex_unlock(&dmabuf->lock); > + =A0 =A0 =A0 return attach; > + > +err_alloc: > + =A0 =A0 =A0 return ERR_PTR(-ENOMEM); > +err_attach: > + =A0 =A0 =A0 kfree(attach); > + =A0 =A0 =A0 mutex_unlock(&dmabuf->lock); > + =A0 =A0 =A0 return ERR_PTR(ret); > +} > +EXPORT_SYMBOL_GPL(dma_buf_attach); > + > +/** > + * dma_buf_detach - Remove the given attachment from dmabuf's attachment= s list; > + * optionally calls detach() of dma_buf_ops for device-specific detach > + * @dmabuf: =A0 =A0[in] =A0 =A0buffer to detach from. > + * @attach: =A0 =A0[in] =A0 =A0attachment to be detached; is free'd afte= r this call. > + * > + */ > +void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *a= ttach) > +{ > + =A0 =A0 =A0 if (WARN_ON(!dmabuf || !attach || !dmabuf->ops)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return; > + > + =A0 =A0 =A0 mutex_lock(&dmabuf->lock); > + =A0 =A0 =A0 list_del(&attach->node); > + =A0 =A0 =A0 if (dmabuf->ops->detach) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 dmabuf->ops->detach(dmabuf, attach); > + > + =A0 =A0 =A0 mutex_unlock(&dmabuf->lock); > + =A0 =A0 =A0 kfree(attach); > +} > +EXPORT_SYMBOL_GPL(dma_buf_detach); > + > +/** > + * dma_buf_map_attachment - Returns the scatterlist table of the attachm= ent; > + * mapped into _device_ address space. Is a wrapper for map_dma_buf() of= the > + * dma_buf_ops. > + * @attach: =A0 =A0[in] =A0 =A0attachment whose scatterlist is to be ret= urned > + * @direction: [in] =A0 =A0direction of DMA transfer > + * > + * Returns sg_table containing the scatterlist to be returned; may retur= n NULL > + * or ERR_PTR. > + * > + */ > +struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attac= h, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 enum dma_data_direction direction) > +{ > + =A0 =A0 =A0 struct sg_table *sg_table =3D ERR_PTR(-EINVAL); > + > + =A0 =A0 =A0 might_sleep(); > + > + =A0 =A0 =A0 if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->= ops)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return ERR_PTR(-EINVAL); > + > + =A0 =A0 =A0 mutex_lock(&attach->dmabuf->lock); > + =A0 =A0 =A0 if (attach->dmabuf->ops->map_dma_buf) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 sg_table =3D attach->dmabuf->ops->map_dma_b= uf(attach, direction); > + =A0 =A0 =A0 mutex_unlock(&attach->dmabuf->lock); > + > + =A0 =A0 =A0 return sg_table; > +} > +EXPORT_SYMBOL_GPL(dma_buf_map_attachment); > + > +/** > + * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffe= r;might > + * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf= () of > + * dma_buf_ops. > + * @attach: =A0 =A0[in] =A0 =A0attachment to unmap buffer from > + * @sg_table: =A0[in] =A0 =A0scatterlist info of the buffer to unmap > + * > + */ > +void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct sg_t= able *sg_table) > +{ > + =A0 =A0 =A0 if (WARN_ON(!attach || !attach->dmabuf || !sg_table > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 || !attach->dmabuf-= >ops)) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return; > + > + =A0 =A0 =A0 mutex_lock(&attach->dmabuf->lock); > + =A0 =A0 =A0 if (attach->dmabuf->ops->unmap_dma_buf) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 attach->dmabuf->ops->unmap_dma_buf(attach, = sg_table); > + =A0 =A0 =A0 mutex_unlock(&attach->dmabuf->lock); > + > +} > +EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > new file mode 100644 > index 0000000..f8ac076 > --- /dev/null > +++ b/include/linux/dma-buf.h > @@ -0,0 +1,176 @@ > +/* > + * Header file for dma buffer sharing framework. > + * > + * Copyright(C) 2011 Linaro Limited. All rights reserved. > + * Author: Sumit Semwal > + * > + * Many thanks to linaro-mm-sig list, and specially > + * Arnd Bergmann , Rob Clark and > + * Daniel Vetter for their support in creation and > + * refining of this idea. > + * > + * This program is free software; you can redistribute it and/or modify = it > + * under the terms of the GNU General Public License version 2 as publis= hed by > + * the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, but W= ITHOUT > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or > + * FITNESS FOR A PARTICULAR PURPOSE. =A0See the GNU General Public Licen= se for > + * more details. > + * > + * You should have received a copy of the GNU General Public License alo= ng with > + * this program. =A0If not, see . > + */ > +#ifndef __DMA_BUF_H__ > +#define __DMA_BUF_H__ > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +struct dma_buf; > +struct dma_buf_attachment; > + > +/** > + * struct dma_buf_ops - operations possible on struct dma_buf > + * @attach: [optional] allows different devices to 'attach' themselves t= o the > + * =A0 =A0 =A0 =A0 given buffer. It might return -EBUSY to signal that b= acking storage > + * =A0 =A0 =A0 =A0 is already allocated and incompatible with the requir= ements > + * =A0 =A0 =A0 =A0 of requesting device. > + * @detach: [optional] detach a given device from this buffer. > + * @map_dma_buf: returns list of scatter pages allocated, increases usec= ount > + * =A0 =A0 =A0 =A0 =A0 =A0 =A0of the buffer. Requires atleast one attach= to be called > + * =A0 =A0 =A0 =A0 =A0 =A0 =A0before. Returned sg list should already be= mapped into > + * =A0 =A0 =A0 =A0 =A0 =A0 =A0_device_ address space. This call may slee= p. May also return > + * =A0 =A0 =A0 =A0 =A0 =A0 =A0-EINTR. Should return -EINVAL if attach ha= sn't been called yet. > + * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatte= r > + * =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0pages. > + * @release: release this buffer; to be called after the last dma_buf_pu= t. > + */ > +struct dma_buf_ops { > + =A0 =A0 =A0 int (*attach)(struct dma_buf *, struct device *, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct dma_buf_attachment *= ); > + > + =A0 =A0 =A0 void (*detach)(struct dma_buf *, struct dma_buf_attachment = *); > + > + =A0 =A0 =A0 /* For {map,unmap}_dma_buf below, any specific buffer attri= butes > + =A0 =A0 =A0 =A0* required should get added to device_dma_parameters acc= essible > + =A0 =A0 =A0 =A0* via dev->dma_params. > + =A0 =A0 =A0 =A0*/ > + =A0 =A0 =A0 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment = *, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 enum dma_data_direction); > + =A0 =A0 =A0 void (*unmap_dma_buf)(struct dma_buf_attachment *, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 struct sg_table *); > + =A0 =A0 =A0 /* TODO: Add try_map_dma_buf version, to return immed with = -EBUSY > + =A0 =A0 =A0 =A0* if the call would block. > + =A0 =A0 =A0 =A0*/ > + > + =A0 =A0 =A0 /* after final dma_buf_put() */ > + =A0 =A0 =A0 void (*release)(struct dma_buf *); > + > +}; > + > +/** > + * struct dma_buf - shared buffer object > + * @size: size of the buffer > + * @file: file pointer used for sharing buffers across, and for refcount= ing. > + * @attachments: list of dma_buf_attachment that denotes all devices att= ached. > + * @ops: dma_buf_ops associated with this buffer object. > + * @priv: exporter specific private data for this buffer object. > + */ > +struct dma_buf { > + =A0 =A0 =A0 size_t size; > + =A0 =A0 =A0 struct file *file; > + =A0 =A0 =A0 struct list_head attachments; > + =A0 =A0 =A0 const struct dma_buf_ops *ops; how about having sg_table here also? like this, struct sg_table *sgt; now dmabuf->priv could have duplicated values. I know that a private buffer object is set to dmabuf->priv when dma_buf_export function is called. but when xxx_acquire_dmabuf callback of vb2 side is called dmabuf->priv would have sg_table object returned from dmabuf->ops->map_dma_buf() again to release the sg_table with dmabuf->ops->unmap_dma_buf(). I'm not sure that this situation could induce some problem but anyway confusing. > + =A0 =A0 =A0 /* mutex to serialize list manipulation and other ops */ > + =A0 =A0 =A0 struct mutex lock; > + =A0 =A0 =A0 void *priv; > +}; > + > +/** > + * struct dma_buf_attachment - holds device-buffer attachment data > + * @dmabuf: buffer for this attachment. > + * @dev: device attached to the buffer. > + * @node: list of dma_buf_attachment. > + * @priv: exporter specific attachment data. > + * > + * This structure holds the attachment information between the dma_buf b= uffer > + * and its user device(s). The list contains one attachment struct per d= evice > + * attached to the buffer. > + */ > +struct dma_buf_attachment { > + =A0 =A0 =A0 struct dma_buf *dmabuf; > + =A0 =A0 =A0 struct device *dev; > + =A0 =A0 =A0 struct list_head node; > + =A0 =A0 =A0 void *priv; > +}; > + > +#ifdef CONFIG_DMA_SHARED_BUFFER > +struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct device *dev); > +void dma_buf_detach(struct dma_buf *dmabuf, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct dma_= buf_attachment *dmabuf_attach); > +struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 size_t size, int flags); > +int dma_buf_fd(struct dma_buf *dmabuf); > +struct dma_buf *dma_buf_get(int fd); > +void dma_buf_put(struct dma_buf *dmabuf); > + > +struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 enum dma_data_direction); > +void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_tab= le *); > +#else > + > +static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *= dmabuf, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct device *dev) > +{ > + =A0 =A0 =A0 return ERR_PTR(-ENODEV); > +} > + > +static inline void dma_buf_detach(struct dma_buf *dmabuf, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct = dma_buf_attachment *dmabuf_attach) > +{ > + =A0 =A0 =A0 return; > +} > + > +static inline struct dma_buf *dma_buf_export(void *priv, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 struct dma_buf_ops *ops, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 size_t size, int flags) > +{ > + =A0 =A0 =A0 return ERR_PTR(-ENODEV); > +} > + > +static inline int dma_buf_fd(struct dma_buf *dmabuf) > +{ > + =A0 =A0 =A0 return -ENODEV; > +} > + > +static inline struct dma_buf *dma_buf_get(int fd) > +{ > + =A0 =A0 =A0 return ERR_PTR(-ENODEV); > +} > + > +static inline void dma_buf_put(struct dma_buf *dmabuf) > +{ > + =A0 =A0 =A0 return; > +} > + > +static inline struct sg_table *dma_buf_map_attachment( > + =A0 =A0 =A0 struct dma_buf_attachment *attach, enum dma_data_direction = write) > +{ > + =A0 =A0 =A0 return ERR_PTR(-ENODEV); > +} > + > +static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *a= ttach, > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 struct sg_table *sg) > +{ > + =A0 =A0 =A0 return; > +} > + > +#endif /* CONFIG_DMA_SHARED_BUFFER */ > + > +#endif /* __DMA_BUF_H__ */ > -- > 1.7.5.4 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. =A0For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter= .ca/ > Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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