RE: [PATCH 1/2] device: add dma_params->max_segment_count
Hello,
On Thursday, July 19, 2012 6:24 PM Rob Clark wrote:
> From: Rob Clark
>
> 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
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
> ---
> 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 Center
--
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RE: [PATCH 1/2] device: add dma_params-max_segment_count
Hello,
On Thursday, July 19, 2012 6:24 PM Rob Clark wrote:
From: Rob Clark r...@ti.com
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 r...@ti.com
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.szyprow...@samsung.com
---
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 RD Center
--
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the body of a message to majord...@vger.kernel.org
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Please read the FAQ at http://www.tux.org/lkml/
