Sidong Yang 05ca530268 drm/vkms: avoid warning in vkms_get_vblank_timestamp
This patch avoid the warning in vkms_get_vblank_timestamp when vblanks
aren't enabled. When running igt test kms_cursor_crc just after vkms
module, the warning raised like below. Initial value of vblank time is
zero and hrtimer.node.expires is also zero if vblank aren't enabled
before. vkms module isn't real hardware but just virtual hardware
module. so vkms can't generate a resonable timestamp when hrtimer is
off. it's best to grab the current time.

[106444.464503] [IGT] kms_cursor_crc: starting subtest pipe-A-cursor-size-change
[106444.471475] WARNING: CPU: 0 PID: 10109 at
vkms_get_vblank_timestamp+0x42/0x50 [vkms]
[106444.471511] CPU: 0 PID: 10109 Comm: kms_cursor_crc Tainted: G        W  OE
5.9.0-rc1+ #6
[106444.471514] RIP: 0010:vkms_get_vblank_timestamp+0x42/0x50 [vkms]
[106444.471528] Call Trace:
[106444.471551]  drm_get_last_vbltimestamp+0xb9/0xd0 [drm]
[106444.471566]  drm_reset_vblank_timestamp+0x63/0xe0 [drm]
[106444.471579]  drm_crtc_vblank_on+0x85/0x150 [drm]
[106444.471582]  vkms_crtc_atomic_enable+0xe/0x10 [vkms]
[106444.471592]  drm_atomic_helper_commit_modeset_enables+0x1db/0x230
[drm_kms_helper]
[106444.471594]  vkms_atomic_commit_tail+0x38/0xc0 [vkms]
[106444.471601]  commit_tail+0x97/0x130 [drm_kms_helper]
[106444.471608]  drm_atomic_helper_commit+0x117/0x140 [drm_kms_helper]
[106444.471622]  drm_atomic_commit+0x4a/0x50 [drm]
[106444.471629]  drm_atomic_helper_set_config+0x63/0xb0 [drm_kms_helper]
[106444.471642]  drm_mode_setcrtc+0x1d9/0x7b0 [drm]
[106444.471654]  ? drm_mode_getcrtc+0x1a0/0x1a0 [drm]
[106444.471666]  drm_ioctl_kernel+0xb6/0x100 [drm]
[106444.471677]  drm_ioctl+0x3ad/0x470 [drm]
[106444.471688]  ? drm_mode_getcrtc+0x1a0/0x1a0 [drm]
[106444.471692]  ? tomoyo_file_ioctl+0x19/0x20
[106444.471694]  __x64_sys_ioctl+0x96/0xd0
[106444.471697]  do_syscall_64+0x37/0x80
[106444.471699]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Cc: Melissa Wen <melissa.srw@gmail.com>

Signed-off-by: Sidong Yang <realwakka@gmail.com>
Reviewed-by: Melissa Wen <melissa.srw@gmail.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200828124553.2178-1-realwakka@gmail.com
2020-08-30 09:27:06 -04:00
2020-08-18 14:14:25 +02:00
2020-08-14 19:56:56 -07:00
2020-08-16 13:04:57 -07:00

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.
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