Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms

[Rob Clark]

Fyi, Daniel Vetter had suggested on IRC that it would be cleaner to
have a single helper fxn that most-restrictive union of all attached
device's dma_parms.  Really this should include dma_mask and
coherent_dma_mask, I think.  But that touches a lot of other places in
the code.  If no one objects to the cleanup of moving
dma_mask/coherent_dma_mask into dma_parms, I'll do this first.

So anyways, don't consider this patch yet for inclusion, I'll make an
updated one based on dma_parms..

BR,
-R

On Thu, Jul 19, 2012 at 11:23 AM, Rob Clark <rob.clark@xxxxxxxxxx> wrote:
> From: Rob Clark <rob@xxxxxx>
>
> Add some helpers to iterate through all attachers and get the most
> restrictive segment size/count/boundary.
>
> Signed-off-by: Rob Clark <rob@xxxxxx>
> ---
>  drivers/base/dma-buf.c  |   63 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/dma-buf.h |   19 ++++++++++++++
>  2 files changed, 82 insertions(+)
>
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 24e88fe..757ee20 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -192,6 +192,69 @@ void dma_buf_put(struct dma_buf *dmabuf)
>  EXPORT_SYMBOL_GPL(dma_buf_put);
>
>  /**
> + * dma_buf_max_seg_size - helper for exporters to get the minimum of
> + * all attached device's max segment size
> + */
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> +       struct dma_buf_attachment *attach;
> +       unsigned int max = (unsigned int)-1;
> +
> +       if (WARN_ON(!dmabuf))
> +               return 0;
> +
> +       mutex_lock(&dmabuf->lock);
> +       list_for_each_entry(attach, &dmabuf->attachments, node)
> +               max = min(max, dma_get_max_seg_size(attach->dev));
> +       mutex_unlock(&dmabuf->lock);
> +
> +       return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_size);
> +
> +/**
> + * dma_buf_max_seg_count - helper for exporters to get the minimum of
> + * all attached device's max segment count
> + */
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> +       struct dma_buf_attachment *attach;
> +       unsigned int max = (unsigned int)-1;
> +
> +       if (WARN_ON(!dmabuf))
> +               return 0;
> +
> +       mutex_lock(&dmabuf->lock);
> +       list_for_each_entry(attach, &dmabuf->attachments, node)
> +               max = min(max, dma_get_max_seg_count(attach->dev));
> +       mutex_unlock(&dmabuf->lock);
> +
> +       return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_count);
> +
> +/**
> + * dma_buf_get_seg_boundary - helper for exporters to get the most
> + * restrictive segment alignment of all the attached devices
> + */
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> +       struct dma_buf_attachment *attach;
> +       unsigned int mask = (unsigned int)-1;
> +
> +       if (WARN_ON(!dmabuf))
> +               return 0;
> +
> +       mutex_lock(&dmabuf->lock);
> +       list_for_each_entry(attach, &dmabuf->attachments, node)
> +               mask &= dma_get_seg_boundary(attach->dev);
> +       mutex_unlock(&dmabuf->lock);
> +
> +       return mask;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_get_seg_boundary);
> +
> +/**
>   * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
>   * calls attach() of dma_buf_ops to allow device-specific attach functionality
>   * @dmabuf:    [in]    buffer to attach device to.
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index eb48f38..9533b9b 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -167,6 +167,10 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
>  struct dma_buf *dma_buf_get(int fd);
>  void dma_buf_put(struct dma_buf *dmabuf);
>
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf);
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf);
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf);
> +
>  struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
>                                         enum dma_data_direction);
>  void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
> @@ -220,6 +224,21 @@ static inline void dma_buf_put(struct dma_buf *dmabuf)
>         return;
>  }
>
> +static inline unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> +       return 0;
> +}
> +
> +static inline unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> +       return 0;
> +}
> +
> +static inline unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> +       return 0;
> +}
> +
>  static inline struct sg_table *dma_buf_map_attachment(
>         struct dma_buf_attachment *attach, enum dma_data_direction write)
>  {
> --
> 1.7.9.5
>
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