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Message-ID: <56C4A712.4050403@xs4all.nl>
Date: Wed, 17 Feb 2016 18:00:02 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Douglas Anderson <dianders@...omium.org>, linux@....linux.org.uk,
mchehab@....samsung.com, robin.murphy@....com, tfiga@...omium.org,
m.szyprowski@...sung.com
Cc: pawel@...iak.com, Dmitry Torokhov <dmitry.torokhov@...il.com>,
hch@...radead.org, kyungmin.park@...sung.com,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/5] videobuf2-dc: Let drivers specify DMA attrs
Hi Doug,
Is there any reason to think that different planes will need different
DMA attrs? I ask because this patch series of mine:
http://www.spinics.net/lists/linux-media/msg97522.html
does away with allocating allocation contexts (struct vb2_dc_conf).
For dma_attr this would mean that struct dma_attrs would probably be implemented
as a struct dma_attrs pointer in the vb2_queue struct once I rebase that patch series
on top of this patch. In other words, the same dma_attrs struct would be used for all
planes.
Second question: would specifying dma_attrs also make sense for videobuf2-dma-sg.c?
Regards,
Hans
On 01/11/2016 06:30 PM, Douglas Anderson wrote:
> From: Tomasz Figa <tfiga@...omium.org>
>
> DMA allocations might be subject to certain reqiurements specific to the
> hardware using the buffers, such as availability of kernel mapping (for
> contents fix-ups in the driver). The only entity that knows them is the
> driver, so it must share this knowledge with vb2-dc.
>
> This patch extends the alloc_ctx initialization interface to let the
> driver specify DMA attrs, which are then stored inside the allocation
> context and will be used for all allocations with that context.
>
> As a side effect, all dma_*_coherent() calls are turned into
> dma_*_attrs() calls, because the attributes need to be carried over
> through all DMA operations.
>
> Signed-off-by: Tomasz Figa <tfiga@...omium.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> Changes in v6: None
> Changes in v5:
> - Let drivers specify DMA attrs new for v5
>
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
>
> drivers/media/v4l2-core/videobuf2-dma-contig.c | 33 +++++++++++++++++---------
> include/media/videobuf2-dma-contig.h | 11 ++++++++-
> 2 files changed, 32 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> index c33127284cfe..5361197f3e57 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> @@ -23,13 +23,16 @@
>
> struct vb2_dc_conf {
> struct device *dev;
> + struct dma_attrs attrs;
> };
>
> struct vb2_dc_buf {
> struct device *dev;
> void *vaddr;
> unsigned long size;
> + void *cookie;
> dma_addr_t dma_addr;
> + struct dma_attrs attrs;
> enum dma_data_direction dma_dir;
> struct sg_table *dma_sgt;
> struct frame_vector *vec;
> @@ -131,7 +134,8 @@ static void vb2_dc_put(void *buf_priv)
> sg_free_table(buf->sgt_base);
> kfree(buf->sgt_base);
> }
> - dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
> + dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
> + &buf->attrs);
> put_device(buf->dev);
> kfree(buf);
> }
> @@ -147,14 +151,18 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size,
> if (!buf)
> return ERR_PTR(-ENOMEM);
>
> - buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
> - GFP_KERNEL | gfp_flags);
> - if (!buf->vaddr) {
> + buf->attrs = conf->attrs;
> + buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
> + GFP_KERNEL | gfp_flags, &buf->attrs);
> + if (!buf->cookie) {
> dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
> kfree(buf);
> return ERR_PTR(-ENOMEM);
> }
>
> + if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, &buf->attrs))
> + buf->vaddr = buf->cookie;
> +
> /* Prevent the device from being released while the buffer is used */
> buf->dev = get_device(dev);
> buf->size = size;
> @@ -185,8 +193,8 @@ static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
> */
> vma->vm_pgoff = 0;
>
> - ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
> - buf->dma_addr, buf->size);
> + ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
> + buf->dma_addr, buf->size, &buf->attrs);
>
> if (ret) {
> pr_err("Remapping memory failed, error: %d\n", ret);
> @@ -329,7 +337,7 @@ static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
> {
> struct vb2_dc_buf *buf = dbuf->priv;
>
> - return buf->vaddr + pgnum * PAGE_SIZE;
> + return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
> }
>
> static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
> @@ -368,8 +376,8 @@ static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
> return NULL;
> }
>
> - ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
> - buf->size);
> + ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
> + buf->size, &buf->attrs);
> if (ret < 0) {
> dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
> kfree(sgt);
> @@ -721,7 +729,8 @@ const struct vb2_mem_ops vb2_dma_contig_memops = {
> };
> EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
>
> -void *vb2_dma_contig_init_ctx(struct device *dev)
> +void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
> + struct dma_attrs *attrs)
> {
> struct vb2_dc_conf *conf;
>
> @@ -730,10 +739,12 @@ void *vb2_dma_contig_init_ctx(struct device *dev)
> return ERR_PTR(-ENOMEM);
>
> conf->dev = dev;
> + if (attrs)
> + conf->attrs = *attrs;
>
> return conf;
> }
> -EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
> +EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx_attrs);
>
> void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
> {
> diff --git a/include/media/videobuf2-dma-contig.h b/include/media/videobuf2-dma-contig.h
> index c33dfa69d7ab..2087c9a68be3 100644
> --- a/include/media/videobuf2-dma-contig.h
> +++ b/include/media/videobuf2-dma-contig.h
> @@ -16,6 +16,8 @@
> #include <media/videobuf2-v4l2.h>
> #include <linux/dma-mapping.h>
>
> +struct dma_attrs;
> +
> static inline dma_addr_t
> vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb, unsigned int plane_no)
> {
> @@ -24,7 +26,14 @@ vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb, unsigned int plane_no)
> return *addr;
> }
>
> -void *vb2_dma_contig_init_ctx(struct device *dev);
> +void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
> + struct dma_attrs *attrs);
> +
> +static inline void *vb2_dma_contig_init_ctx(struct device *dev)
> +{
> + return vb2_dma_contig_init_ctx_attrs(dev, NULL);
> +}
> +
> void vb2_dma_contig_cleanup_ctx(void *alloc_ctx);
>
> extern const struct vb2_mem_ops vb2_dma_contig_memops;
>
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