Commit b8c5e7b1 authored by Lucas Stach's avatar Lucas Stach Committed by Greg Kroah-Hartman

drm/etnaviv: trick drm_mm into giving out a low IOVA


[ Upstream commit 3546fb0c ]

After rollover of the IOVA space, we want to get a low IOVA address,
otherwise the the games we play by remembering the last IOVA are
pointless. When we search for a free hole with DRM_MM_SEARCH_DEFAULT,
drm_mm will pop the next entry from the free holes stack, which will
likely be a high IOVA. By using DRM_MM_SEARCH_BELOW we can trick
drm_mm into reversing the search and provide us with a low IOVA.
Signed-off-by: default avatarLucas Stach <l.stach@pengutronix.de>
Reviewed-by: default avatarWladimir van der Laan <laanwj@gmail.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2bc8fcd6
......@@ -116,9 +116,14 @@ static int etnaviv_iommu_find_iova(struct etnaviv_iommu *mmu,
struct list_head list;
bool found;
/*
* XXX: The DRM_MM_SEARCH_BELOW is really a hack to trick
* drm_mm into giving out a low IOVA after address space
* rollover. This needs a proper fix.
*/
ret = drm_mm_insert_node_in_range(&mmu->mm, node,
size, 0, mmu->last_iova, ~0UL,
DRM_MM_SEARCH_DEFAULT);
mmu->last_iova ? DRM_MM_SEARCH_DEFAULT : DRM_MM_SEARCH_BELOW);
if (ret != -ENOSPC)
break;
......
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