| Message ID | 1462812247-3414-4-git-send-email-niklas.soderlund+renesas@ragnatech.se (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> > -In some circumstances dma_map_single() and dma_map_page() will fail to create > -a mapping. A driver can check for these errors by testing the returned > -DMA address with dma_mapping_error(). A non-zero return value means the mapping > -could not be created and the driver should take appropriate action (e.g. > -reduce current DMA mapping usage or delay and try again later). > +In some circumstances dma_map_single(), dma_map_page() and dma_map_resource() > +will fail to create a mapping. A driver can check for these errors by testing > +the returned DMA address with dma_mapping_error(). A non-zero return value > +means the mapping could not be created and the driver should take appropriate > +action (e.g. reduce current DMA mapping usage or delay and try again later). This looks like it belongs to another patch?
Hi Konrad, Thanks for your feedback. On 2016-05-17 10:54:45 -0400, Konrad Rzeszutek Wilk wrote: > > > > -In some circumstances dma_map_single() and dma_map_page() will fail to create > > -a mapping. A driver can check for these errors by testing the returned > > -DMA address with dma_mapping_error(). A non-zero return value means the mapping > > -could not be created and the driver should take appropriate action (e.g. > > -reduce current DMA mapping usage or delay and try again later). > > +In some circumstances dma_map_single(), dma_map_page() and dma_map_resource() > > +will fail to create a mapping. A driver can check for these errors by testing > > +the returned DMA address with dma_mapping_error(). A non-zero return value > > +means the mapping could not be created and the driver should take appropriate > > +action (e.g. reduce current DMA mapping usage or delay and try again later). > > This looks like it belongs to another patch? No it is correct (at least intended to be in this patch). All it really do is inject dma_map_resource() (which is added in this patch) as one of the calls which return dma_addr_t should be checked for error using dma_mapping_error(). But yes the change effect all lines in the paragraph due to line wrapping. Hum or maybe I'm misunderstanding your question.
On Thu, May 19, 2016 at 01:29:26PM +0200, Niklas Söderlund wrote: > Hi Konrad, > > Thanks for your feedback. > > On 2016-05-17 10:54:45 -0400, Konrad Rzeszutek Wilk wrote: > > > > > > -In some circumstances dma_map_single() and dma_map_page() will fail to create > > > -a mapping. A driver can check for these errors by testing the returned > > > -DMA address with dma_mapping_error(). A non-zero return value means the mapping > > > -could not be created and the driver should take appropriate action (e.g. > > > -reduce current DMA mapping usage or delay and try again later). > > > +In some circumstances dma_map_single(), dma_map_page() and dma_map_resource() > > > +will fail to create a mapping. A driver can check for these errors by testing > > > +the returned DMA address with dma_mapping_error(). A non-zero return value > > > +means the mapping could not be created and the driver should take appropriate > > > +action (e.g. reduce current DMA mapping usage or delay and try again later). > > > > This looks like it belongs to another patch? > > No it is correct (at least intended to be in this patch). All it really > do is inject dma_map_resource() (which is added in this patch) as one of > the calls which return dma_addr_t should be checked for error using > dma_mapping_error(). But yes the change effect all lines in the > paragraph due to line wrapping. > > Hum or maybe I'm misunderstanding your question. I totally missed the 'dma_map_resource' in there and just read 'dma_mapping_error'! <sigh> Thanks. > > -- > Regards, > Niklas Söderlund
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 45ef3f2..c7e5f99 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -277,14 +277,26 @@ and <size> parameters are provided to do partial page mapping, it is recommended that you never use these unless you really know what the cache width is. +dma_addr_t +dma_map_resource(struct device *dev, phys_addr_t phys_addr, size_t size, + enum dma_data_direction dir, struct dma_attrs *attrs) + +void +dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size, + enum dma_data_direction dir, struct dma_attrs *attrs) + +API for mapping and unmapping for MMIO resources. All the notes and +warnings for the other mapping APIs apply here. The API should only be +used to map device MMIO resources, mapping of RAM is not permitted. + int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) -In some circumstances dma_map_single() and dma_map_page() will fail to create -a mapping. A driver can check for these errors by testing the returned -DMA address with dma_mapping_error(). A non-zero return value means the mapping -could not be created and the driver should take appropriate action (e.g. -reduce current DMA mapping usage or delay and try again later). +In some circumstances dma_map_single(), dma_map_page() and dma_map_resource() +will fail to create a mapping. A driver can check for these errors by testing +the returned DMA address with dma_mapping_error(). A non-zero return value +means the mapping could not be created and the driver should take appropriate +action (e.g. reduce current DMA mapping usage or delay and try again later). int dma_map_sg(struct device *dev, struct scatterlist *sg, diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 8617fa1..dd228ce 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -218,6 +218,42 @@ static inline void dma_unmap_page(struct device *dev, dma_addr_t addr, debug_dma_unmap_page(dev, addr, size, dir, false); } +static inline dma_addr_t dma_map_resource(struct device *dev, + phys_addr_t phys_addr, + size_t size, + enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + struct dma_map_ops *ops = get_dma_ops(dev); + unsigned long pfn = __phys_to_pfn(phys_addr); + dma_addr_t addr; + + BUG_ON(!valid_dma_direction(dir)); + + /* Don't allow RAM to be mapped */ + BUG_ON(pfn_valid(pfn)); + + addr = phys_addr; + if (ops->map_resource) + addr = ops->map_resource(dev, phys_addr, size, dir, attrs); + + debug_dma_map_resource(dev, phys_addr, size, dir, addr); + + return addr; +} + +static inline void dma_unmap_resource(struct device *dev, dma_addr_t addr, + size_t size, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + struct dma_map_ops *ops = get_dma_ops(dev); + + BUG_ON(!valid_dma_direction(dir)); + if (ops->unmap_resource) + ops->unmap_resource(dev, addr, size, dir, attrs); + debug_dma_unmap_resource(dev, addr, size, dir); +} + static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size, enum dma_data_direction dir)
Map/Unmap a device MMIO resource from a physical address. If no dma_map_ops method is available the operation is a no-op. Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> --- Documentation/DMA-API.txt | 22 +++++++++++++++++----- include/linux/dma-mapping.h | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+), 5 deletions(-)