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8b18658736
The crc computation worker needs to be able to get at some data structures and framebuffer mappings, while potentially more atomic updates are going on. The solution thus far is to copy relevant bits around, but that's very tedious. Here's a new approach, which tries to be more clever, but relies on a few not-so-obvious things: - crtc_state is always updated when a plane_state changes. Therefore we can just stuff plane_state pointers into a crtc_state. That solves the problem of easily getting at the needed plane_states. - with the flushing changes from previous patches the above also holds without races due to the next atomic update being a bit eager with cleaning up pending work - we always wait for all crc work items to complete before unmapping framebuffers. - we also need to make sure that the hrtimer fires off the right worker. Keep a new distinct crc_state pointer, under the vkms_output->lock protection for this. Note that crtc->state is updated very early in the atomic commit, way before we arm the vblank event - the vblank event should always match the buffers we use to compute the crc. This also solves an issue in the hrtimer, where we've accessed drm_crtc->state without holding the right locks (we held none - oops). - in the worker itself we can then just access the plane states we need, again solving a bunch of ordering and locking issues. Accessing plane->state requires locks, accessing the private vkms_crtc_state->active_planes pointer only requires that the memory doesn't get freed too early. The idea behind vkms_crtc_state->active_planes is that this would contain all visible planes, in z-order, as a first step towards a more generic blending implementation. Note that this patch also fixes races between prepare_fb/cleanup_fb and the crc worker accessing ->vaddr. Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Cc: Haneen Mohammed <hamohammed.sa@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Tested-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190606222751.32567-10-daniel.vetter@ffwll.ch |
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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 Restructured Text 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.