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VKMS needs vblank interrupts enabled to capture CRC. When vblank is disabled, tests like kms_cursor_crc and kms_pipe_crc_basic getting stuck waiting for a capture that will not occur until vkms wakes up. This patch adds a helper to set composer and ensure that vblank remains enabled as long as the CRC capture is needed. It clears the execution of the following kms_cursor_crc subtests: 1. pipe-A-cursor-[size,alpha-opaque, NxN-(on-screen, off-screen, sliding, random, fast-moving])] - successful when running individually. 2. pipe-A-cursor-dpms passes again 3. pipe-A-cursor-suspend also passes The issue was initially tracked in the sequential execution of IGT kms_cursor_crc subtests: when running the test sequence or one of its subtests twice, the odd execs complete and the pairs get stuck in an endless wait. In the IGT code, calling a wait_for_vblank on preparing for CRC capture prevented the busy-wait. But the problem persisted in the pipe-A-cursor-dpms and -suspend subtests. Checking the history, the pipe-A-cursor-dpms subtest was successful when, in vkms_atomic_commit_tail, instead of using the flip_done op, it used wait_for_vblanks. Another way to prevent blocking was wait_one_vblank when enabling crtc. However, in both cases, pipe-A-cursor-suspend persisted blocking in the 2nd start of CRC capture, which may indicate that something got stuck in the step of CRC setup. Indeed, wait_one_vblank in the crc setup was able to sync things and free all kms_cursor_crc subtests. Besides, other alternatives to force enabling vblanks or prevent disabling them such as calling drm_crtc_put_vblank or modeset_enables before commit_planes + offdelay = 0, also unlock all subtests executions. Finally, due to vkms's dependence on vblank interruptions to perform tasks, this patch uses refcount to ensure that vblanks happen when enabling composer and while crc capture is needed. Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Cc: Haneen Mohammed <hamohammed.sa@gmail.com> v2: - extract a vkms_set_composer helper - fix vblank refcounting for the disabling case v3: - make the vkms_set_composer helper static - review the credit tags Co-debugged-by: Sidong Yang <realwakka@gmail.com> Signed-off-by: Sidong Yang <realwakka@gmail.com> Signed-off-by: Melissa Wen <melissa.srw@gmail.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> [danvet: add changelog back in] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200808120900.pudwwrfz44g3rqx7@smtp.gmail.com |
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| ipc | ||
| kernel | ||
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| README | ||
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.