• Oleksandr Andrushchenko's avatar
    drm/xen-front: Remove CMA support · 4394e964
    Oleksandr Andrushchenko authored
    It turns out this was only needed to paper over a bug in the CMA
    helpers, which was addressed in
    commit 998fb1a0
    Author: Liviu Dudau <Liviu.Dudau@arm.com>
    Date:   Fri Nov 10 13:33:10 2017 +0000
        drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1
    Without this the following pipeline didn't work:
    1. xen-front allocates a non-contig buffer
    2. creates grants out of it
    3. converts the grants into a dma-buf. Since they're non-contig, the
    scatter-list is huge.
    4. imports it into rcar-du, which requires dma-contig memory for
    -> On this given platform there's an IOMMU, so in theory this should
    work. But in practice this failed, because of the huge number of sg
    entries, even though the IOMMU driver mapped it all into a dma-contig
    With a guest-contig buffer allocated in step 1, this problem doesn't
    exist. But there's technically no reason to require guest-contig
    memory for xen buffer sharing using grants.
    Given all that, the xen-front cma support is not needed and should be
    Signed-off-by: default avatarOleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
    Suggested-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    Link: https://patchwork.freedesktop.org/patch/msgid/20180417074012.21311-1-andr2000@gmail.com