Hello,
On Thursday, July 19, 2012 6:24 PM Rob Clark wrote:
> From: Rob Clark <rob@xxxxxx>
>
> For devices which have constraints about maximum number of segments
> in an sglist. For example, a device which could only deal with
> contiguous buffers would set max_segment_count to 1.
>
> The initial motivation is for devices sharing buffers via dma-buf,
> to allow the buffer exporter to know the constraints of other
> devices which have attached to the buffer. The dma_mask and fields
> in 'struct device_dma_parameters' tell the exporter everything else
> that is needed, except whether the importer has constraints about
> maximum number of segments.
>
> Signed-off-by: Rob Clark <rob@xxxxxx>
Yea, it is a really good idea to add this to struct device_dma_parameters.
We only need to initialize it to '1' in platform startup code for all
devices relevant to buffer sharing.
Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> include/linux/device.h | 1 +
> include/linux/dma-mapping.h | 16 ++++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 161d962..3813735 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -568,6 +568,7 @@ struct device_dma_parameters {
> * sg limitations.
> */
> unsigned int max_segment_size;
> + unsigned int max_segment_count; /* zero for unlimited */
> unsigned long segment_boundary_mask;
> };
>
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index dfc099e..f380f79 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -111,6 +111,22 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev,
> return -EIO;
> }
>
> +static inline unsigned int dma_get_max_seg_count(struct device *dev)
> +{
> + return dev->dma_parms ? dev->dma_parms->max_segment_count : 0;
> +}
> +
> +static inline int dma_set_max_seg_count(struct device *dev,
> + unsigned int count)
> +{
> + if (dev->dma_parms) {
> + dev->dma_parms->max_segment_count = count;
> + return 0;
> + } else
> + return -EIO;
> +}
> +
> +
> static inline unsigned long dma_get_seg_boundary(struct device *dev)
> {
> return dev->dma_parms ?
> --
> 1.7.9.5
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
