On Tue, Sep 22, 2020 at 01:56:46PM +0000, David Laight wrote: > > +/* > > + * A dma_addr_t can hold any valid DMA or bus address for the platform. > > It can > > + * be given to a device to use as a DMA source or target. A CPU cannot > > + * reference a dma_addr_t directly because there may be translation > > between its > > + * physical address space and the bus address space. > > It can't access it 'directly' because it isn't a virtual address.... > > > + * > > + * DMA_MAPPING_ERROR is the magic error code if a mapping failed. It > > should not > > + * be used directly in drivers, but checked for using dma_mapping_error() > > + * instead. > > + */ > > I think it might be worth adding: > > A dma_addr_t value may be device dependant and differ from the > 'physical address' of the memory.
This is what I've committed: * A dma_addr_t can hold any valid DMA or bus address for the platform. It can * be given to a device to use as a DMA source or target. It is specific to a * given device and there may be a translation between the CPU physical address * space and the bus address space. _______________________________________________ iommu mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/iommu