From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Tomasz Figa <tfiga@chromium.org>,
Ricardo Ribalda <ribalda@chromium.org>,
Christoph Hellwig <hch@lst.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 8/8] videobuf2: handle non-contiguous DMA allocations
Date: Thu, 17 Jun 2021 16:56:17 +0900 [thread overview]
Message-ID: <YMsAIVs7G2hUDR2F@google.com> (raw)
In-Reply-To: <10a0903a-e295-5cba-683a-1eb89a0804ed@xs4all.nl>
On (21/06/03 13:59), Hans Verkuil wrote:
[[.]
> > static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
> > {
> > struct vb2_dc_buf *buf = buf_priv;
> > - struct dma_buf_map map;
> > - int ret;
> >
> > - if (!buf->vaddr && buf->db_attach) {
> > - ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
> > - buf->vaddr = ret ? NULL : map.vaddr;
> > + if (buf->vaddr)
> > + return buf->vaddr;
> > +
> > + if (buf->db_attach) {
> > + struct dma_buf_map map;
> > +
> > + if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
> > + buf->vaddr = map.vaddr;
> > +
> > + return buf->vaddr;
> > }
> >
> > + /* Non-coherent memory */
> > + buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size, buf->dma_sgt);
> > +
>
> This function can use some comments. What is happening AFAICS is that
> buf->vaddr is either set in vb2_dc_alloc_coherent (unless
> DMA_ATTR_NO_KERNEL_MAPPING was set), it is obtained through dma_buf_vmap()
> if the buffer was attached to a dma_buf, or it is allocated via
> dma_vmap_noncontiguous() for non-coherent memory.
Yeah, it's complicated. Maybe we can make things more symmetrical.
> But this leaves coherent memory with DMA_ATTR_NO_KERNEL_MAPPING set, what
> is vaddr in that case? I think it will call dma_vmap_noncontiguous()
> incorrectly in that case, shouldn't there be a check for !buf->coherent_mem
> before the call to dma_vmap_noncontiguous()?
Thanks a lot for looking into it.
So vb2_dc_vaddr() can look like this:
static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
{
struct vb2_dc_buf *buf = buf_priv;
if (buf->vaddr)
return buf->vaddr;
if (buf->db_attach) {
struct dma_buf_map map;
if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
buf->vaddr = map.vaddr;
return buf->vaddr;
}
if (!buf->coherent_mem)
buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size,
buf->dma_sgt);
return buf->vaddr;
}
And in vb2_dc_alloc functions set vaddr for !DMA_ATTR_NO_KERNEL_MAPPING
in both coherent and non-coherent. So that we probably can have less
branches when ->vaddr is NULL for one type of allocations, and is not
NULL for another.
static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf)
{
struct vb2_queue *q = buf->vb->vb2_queue;
buf->cookie = dma_alloc_attrs(buf->dev,
buf->size,
&buf->dma_addr,
GFP_KERNEL | q->gfp_flags,
buf->attrs);
if (!buf->cookie)
return -ENOMEM;
if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
return 0;
buf->vaddr = buf->cookie;
return 0;
}
static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf)
{
struct vb2_queue *q = buf->vb->vb2_queue;
buf->dma_sgt = dma_alloc_noncontiguous(buf->dev,
buf->size,
buf->dma_dir,
GFP_KERNEL | q->gfp_flags,
buf->attrs);
if (!buf->dma_sgt)
return -ENOMEM;
if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
return 0;
buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size, buf->dma_sgt);
if (!buf->vaddr) {
dma_free_noncontiguous(buf->dev, buf->size,
buf->dma_sgt, buf->dma_addr);
return -ENOMEM;
}
return 0;
}
next prev parent reply other threads:[~2021-06-17 7:56 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 13:13 [PATCHv2 0/8] videobuf2: support new noncontiguous DMA API Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 1/8] videobuf2: rework vb2_mem_ops API Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 2/8] videobuf2: inverse buffer cache_hints flags Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 3/8] videobuf2: split buffer cache_hints initialisation Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 4/8] videobuf2: move cache_hints handling to allocators Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 5/8] videobuf2: add V4L2_MEMORY_FLAG_NON_COHERENT flag Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 6/8] videobuf2: add queue memory coherency parameter Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag Sergey Senozhatsky
2021-05-01 3:48 ` Sergey Senozhatsky
2021-06-03 11:32 ` Hans Verkuil
2021-06-17 1:46 ` Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 8/8] videobuf2: handle non-contiguous DMA allocations Sergey Senozhatsky
2021-04-28 6:14 ` Christoph Hellwig
2021-06-03 11:59 ` Hans Verkuil
2021-06-17 7:56 ` Sergey Senozhatsky [this message]
2021-06-17 8:01 ` Christoph Hellwig
2021-06-17 8:30 ` Tomasz Figa
2021-06-17 8:52 ` Christoph Hellwig
2021-06-17 9:40 ` Tomasz Figa
2021-06-17 10:06 ` Christoph Hellwig
2021-06-18 3:21 ` Tomasz Figa
2021-06-18 4:25 ` Christoph Hellwig
2021-06-18 4:44 ` Tomasz Figa
2021-06-22 7:33 ` Christoph Hellwig
2021-07-07 12:42 ` Tomasz Figa
2021-06-25 3:10 ` Sergey Senozhatsky
2021-07-07 12:48 ` Tomasz Figa
2021-07-07 13:29 ` Sergey Senozhatsky
2021-07-07 14:10 ` Tomasz Figa
2021-07-09 7:20 ` Sergey Senozhatsky
2021-06-17 7:56 ` Sergey Senozhatsky
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