Re: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wednesday 19 September 2012, Hiroshi Doyu wrote:
> I guess that it would work. Originally I thought that using DMA-API
> and IOMMU-API together in driver might be kind of layering violation
> since IOMMU-API itself is used in DMA-API. Only DMA-API used in driver
> might be cleaner. Considering that DMA API traditionally handling
> anonymous {bus,iova} address only, introducing the concept of
> specific address in DMA API may not be so encouraged, though.
> 
> It would be nice to listen how other SoCs have solved similar needs.

In general, I would recommend using only the IOMMU API when you have a device
driver that needs to control the bus virtual address space and that manages
a device that resides in its own IOMMU context. I would recommend using
only the dma-mapping API when you have a device that lives in a shared
bus virtual address space with other devices, and then never ask for
a specific bus virtual address.

Can you explain what devices you see that don't fit in one of those two
categories?

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-tegra" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [ARM Kernel]     [Linux ARM]     [Linux ARM MSM]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux