Messages in this thread | | | Date | Fri, 14 Mar 2014 17:12:03 +0100 | From | Tomasz Figa <> | Subject | Re: [PATCH v11 20/27] iommu/exynos: allow having multiple System MMUs for a master H/W |
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Hi KyongHo,
On 14.03.2014 06:10, Cho KyongHo wrote: > Some master device descriptor like fimc-is which is an abstraction > of very complex H/W may have multiple System MMUs. For those devices, > the design of the link between System MMU and its master H/W is needed > to be reconsidered. > > A link structure, sysmmu_list_data is introduced that provides a link > to master H/W and that has a pointer to the device descriptor of a > System MMU. Given a device descriptor of a master H/W, it is possible > to traverse all System MMUs that must be controlled along with the > master H/W.
NAK.
A device driver should handle particular hardware instances separately, without abstracting a virtual hardware instance consisting of multiple physical ones.
If such abstraction is needed, it should be done above the exynos-iommu driver, e.g. by something like iommu-composite driver that would aggregate several IOMMUs. Keep in mind that such IOMMUs in a group could be different, e.g. different Exynos SysMMU versions or even completely different IPs handled by different drivers.
Still, I don't think there is a real need for such abstraction. Instead, related drivers shall be fixed to properly handle multiple memory masters and their IOMMUs.
Best regards, Tomasz
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