Re: [RFC PATCH v1 4/7] media: videobuf2: introduce VIDEOBUF2_PAGE memops

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Hi Ming,

On Fri, Dec 2, 2011 at 3:12 AM, Ming Lei <ming.lei@xxxxxxxxxxxxx> wrote:
> DMA contig memory resource is very limited and precious, also
> accessing to it from CPU is very slow on some platform.
>
> For some cases(such as the comming face detection driver), DMA Streaming
> buffer is enough, so introduce VIDEOBUF2_PAGE to allocate continuous
> physical memory but letting video device driver to handle DMA buffer mapping
> and unmapping things.
>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
> ---
>  drivers/media/video/Kconfig          |    4 +
>  drivers/media/video/Makefile         |    1 +
>  drivers/media/video/videobuf2-page.c |  115 ++++++++++++++++++++++++++++++++++
>  include/media/videobuf2-page.h       |   20 ++++++
>  4 files changed, 140 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/media/video/videobuf2-page.c
>  create mode 100644 include/media/videobuf2-page.h
>
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index 4e8a0c4..5684a00 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -60,6 +60,10 @@ config VIDEOBUF2_VMALLOC
>        select VIDEOBUF2_MEMOPS
>        tristate
>
> +config VIDEOBUF2_PAGE
> +       select VIDEOBUF2_CORE
> +       select VIDEOBUF2_MEMOPS
> +       tristate
>
>  config VIDEOBUF2_DMA_SG
>        #depends on HAS_DMA
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index ddeaa6c..bc797f2 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -125,6 +125,7 @@ obj-$(CONFIG_VIDEO_BTCX)  += btcx-risc.o
>  obj-$(CONFIG_VIDEOBUF2_CORE)           += videobuf2-core.o
>  obj-$(CONFIG_VIDEOBUF2_MEMOPS)         += videobuf2-memops.o
>  obj-$(CONFIG_VIDEOBUF2_VMALLOC)                += videobuf2-vmalloc.o
> +obj-$(CONFIG_VIDEOBUF2_PAGE)           += videobuf2-page.o
>  obj-$(CONFIG_VIDEOBUF2_DMA_CONTIG)     += videobuf2-dma-contig.o
>  obj-$(CONFIG_VIDEOBUF2_DMA_SG)         += videobuf2-dma-sg.o
>
> diff --git a/drivers/media/video/videobuf2-page.c b/drivers/media/video/videobuf2-page.c
> new file mode 100644
> index 0000000..b3f003a
> --- /dev/null
> +++ b/drivers/media/video/videobuf2-page.c
> @@ -0,0 +1,115 @@
> +/*
> + * videobuf2-page.c - page memory allocator for videobuf2
> + *
> + * Copyright (C) 2011 Canonical Ltd.
> + *
> + * Author: Ming Lei <ming.lei@xxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/mm.h>
> +#include <linux/slab.h>
> +
> +#include <media/videobuf2-core.h>
> +#include <media/videobuf2-memops.h>
> +
> +struct vb2_page_buf {
> +       void                            *vaddr;
> +       unsigned long                   size;
> +       atomic_t                        refcount;
> +       struct vb2_vmarea_handler       handler;
> +};
> +
> +static void vb2_page_put(void *buf_priv);
> +
> +static void *vb2_page_alloc(void *alloc_ctx, unsigned long size)
> +{
> +       struct vb2_page_buf *buf;
> +
> +       buf = kzalloc(sizeof *buf, GFP_KERNEL);
> +       if (!buf)
> +               return NULL;
> +
> +       buf->size = size;
> +       buf->vaddr = (void *)__get_free_pages(GFP_KERNEL,
> +                       get_order(buf->size));
> +       buf->handler.refcount = &buf->refcount;
> +       buf->handler.put = vb2_page_put;
> +       buf->handler.arg = buf;
> +
> +       if (!buf->vaddr) {
> +               printk(KERN_ERR "page of size %ld failed\n", buf->size);
> +               kfree(buf);
> +               return NULL;
> +       }
> +
> +       atomic_inc(&buf->refcount);
> +       printk(KERN_DEBUG "Allocated page buffer of size %ld at vaddr=%p\n",
> +                       buf->size, buf->vaddr);
> +
> +       return buf;
> +}
> +
> +static void vb2_page_put(void *buf_priv)
> +{
> +       struct vb2_page_buf *buf = buf_priv;
> +
> +       if (atomic_dec_and_test(&buf->refcount)) {
> +               printk(KERN_DEBUG "%s: Freeing page mem at vaddr=%p\n",
> +                       __func__, buf->vaddr);
> +               free_pages((unsigned long)buf->vaddr, get_order(buf->size));
> +               kfree(buf);
> +       }
> +}
> +
> +static void *vb2_page_vaddr(void *buf_priv)
> +{
> +       struct vb2_page_buf *buf = buf_priv;
> +
> +       BUG_ON(!buf);
> +
> +       if (!buf->vaddr) {
> +               printk(KERN_ERR "Address of an unallocated plane requested\n");
> +               return NULL;
> +       }
> +
> +       return buf->vaddr;
> +}
> +
> +static unsigned int vb2_page_num_users(void *buf_priv)
> +{
> +       struct vb2_page_buf *buf = buf_priv;
> +       return atomic_read(&buf->refcount);
> +}
> +
> +static int vb2_page_mmap(void *buf_priv, struct vm_area_struct *vma)
> +{
> +       struct vb2_page_buf *buf = buf_priv;
> +
> +       if (!buf) {
> +               printk(KERN_ERR "No memory to map\n");
> +               return -EINVAL;
> +       }
> +
> +       vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> +       return vb2_mmap_pfn_range(vma, virt_to_phys(buf->vaddr),
> +                       buf->size, &vb2_common_vm_ops,
> +                       &buf->handler);
> +}
> +
> +const struct vb2_mem_ops vb2_page_memops = {
> +       .alloc          = vb2_page_alloc,
> +       .put            = vb2_page_put,
> +       .vaddr          = vb2_page_vaddr,
> +       .mmap           = vb2_page_mmap,
> +       .num_users      = vb2_page_num_users,
> +};
> +EXPORT_SYMBOL_GPL(vb2_page_memops);
> +
> +MODULE_DESCRIPTION("page memory handling routines for videobuf2");
> +MODULE_AUTHOR("Ming Lei");
> +MODULE_LICENSE("GPL");
> diff --git a/include/media/videobuf2-page.h b/include/media/videobuf2-page.h
> new file mode 100644
> index 0000000..29b3e20
> --- /dev/null
> +++ b/include/media/videobuf2-page.h
> @@ -0,0 +1,20 @@
> +/*
> + * videobuf2-vmalloc.h - vmalloc memory allocator for videobuf2
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <pawel@xxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +
> +#ifndef _MEDIA_VIDEOBUF2_VMALLOC_H
> +#define _MEDIA_VIDEOBUF2_VMALLOC_H

Copy-paste much? :)

Fix header and match above define with something that matches the actual file:

#ifndef _MEDIA_VIDEOBUF2_PAGE_H
#define _MEDIA_VIDEOBUF2_PAGE_H

Regards,
Sergio

> +
> +#include <media/videobuf2-core.h>
> +
> +extern const struct vb2_mem_ops vb2_page_memops;
> +
> +#endif
> --
> 1.7.5.4
>
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