On 09/20/2012 12:40 AM, Krishna Reddy wrote: >>> On Tegra, the following use cases need specific IOVA mapping. >>> 1. Few MMIO blocks need IOVA=PA mapping setup. >> >> In that case, why would we enable the IOMMU for that one device; IOMMU >> disabled means VA==PA, right? Perhaps isolation of the device so it can only >> access certain PA ranges for security? > > The device(H/W controller) need to access few special memory blocks(IOVA==PA) > and DRAM as well.
OK, so only /some/ of the VA space is VA==PA, and some is remapped; that's a little different that what you originally implied above. BTW, which HW module is this; AVP/COP or something else. This sounds like an odd requirement. > There is also a case where frame buffer memory is passed from BootLoader to > Kernel and > display H/W continues to access it with IOMMU enabled. To support this, the > one to one > mapping has to be setup before enabling IOMMU. Yes, that makes sense. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
