| Message ID | 1342715014-5316-2-git-send-email-rob.clark@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hello, On Thursday, July 19, 2012 6:24 PM Rob Clark wrote: > From: Rob Clark <rob@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 <rob@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.szyprowski@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
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 ?