lkml.org 
[lkml]   [2014]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v11 20/27] iommu/exynos: allow having multiple System MMUs for a master H/W
    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


    \
     
     \ /
      Last update: 2014-03-14 18:01    [W:3.140 / U:0.284 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site