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Leo Li
38e0c3df6d
[Why] Compositors have different ways of assigning surfaces to DRM planes for render offloading. It may decide between various strategies: overlay, underlay, or a mix of both (see here for more info: https://gitlab.freedesktop.org/emersion/libliftoff/-/issues/76) One way for compositors to implement the underlay strategy is to assign a higher zpos to the DRM_PRIMARY plane than the DRM_OVERLAY planes, effectively turning the DRM_OVERLAY plane into an underlay plane. Today, amdgpu attaches an immutable zpos of 0 to the DRM_PRIMARY plane. This however, is an arbitrary restriction. DCN pipes are general purpose, and can be arranged in any z-order. To support compositors using this allocation scheme, we can set a non-zero immutable zpos for the PRIMARY, allowing the placement of OVERLAYS (mutable zpos range 0-254) beneath the PRIMARY. [How] Assign a zpos = #no of OVERLAY planes to the PRIMARY plane. Then, clean up any assumptions in the driver of PRIMARY plane having the lowest zpos. v2: Fix typo s/decending/descending/ Reviewed-by: Harry Wentland <harry.wentland@amd.com> Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com> Signed-off-by: Leo Li <sunpeng.li@amd.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.