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author | Benjamin Gaignard <benjamin.gaignard@linaro.org> | 2017-01-04 10:12:57 +0100 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-01-06 11:04:54 +0100 |
commit | 62a0d98a188cc4ebd8ea54b37d274ec20465e464 (patch) | |
tree | bb649f5cc408727179380fce600adeba99b2ebbd /Documentation/gpu | |
parent | 99c48e1e38f0aeaa107ad67c8d91f6c9d9d567a9 (diff) | |
download | op-kernel-dev-62a0d98a188cc4ebd8ea54b37d274ec20465e464.zip op-kernel-dev-62a0d98a188cc4ebd8ea54b37d274ec20465e464.tar.gz |
drm: allow to use mmuless SoC
Some SoC without MMU have display driver where a drm/kms driver
could be implemented.
Before doing such kind of thing drm/kms must allow to use mmuless devices.
This patch propose to remove MMU configuration flag and add a cma helper
function to help implementing mmuless display driver
version 4:
- add documentation about drm_gem_cma_get_unmapped_area()
- stub it MMU case
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
[danvet: Use recommended struct member references in kernel-doc.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1483521177-21794-4-git-send-email-benjamin.gaignard@linaro.org
Diffstat (limited to 'Documentation/gpu')
-rw-r--r-- | Documentation/gpu/drm-mm.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst index d3c6d77..1ea94fc 100644 --- a/Documentation/gpu/drm-mm.rst +++ b/Documentation/gpu/drm-mm.rst @@ -310,6 +310,17 @@ created. Drivers that want to map the GEM object upfront instead of handling page faults can implement their own mmap file operation handler. +For platforms without MMU the GEM core provides a helper method +:c:func:`drm_gem_cma_get_unmapped_area`. The mmap() routines will call +this to get a proposed address for the mapping. + +To use :c:func:`drm_gem_cma_get_unmapped_area`, drivers must fill the +struct :c:type:`struct file_operations <file_operations>` get_unmapped_area +field with a pointer on :c:func:`drm_gem_cma_get_unmapped_area`. + +More detailed information about get_unmapped_area can be found in +Documentation/nommu-mmap.txt + Memory Coherency ---------------- |