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drm/vkms: avoid warning in vkms_get_vblank_timestamp
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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
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@realwakka @rodrigosiqueira
realwakka authored and rodrigosiqueira committed Aug 30, 2020
1 parent 39cba5c commit 05ca530
Showing 1 changed file with 5 additions and 0 deletions.
5 changes: 5 additions & 0 deletions drivers/gpu/drm/vkms/vkms_crtc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,11 @@ static bool vkms_get_vblank_timestamp(struct drm_crtc *crtc,
struct vkms_output *output = &vkmsdev->output;
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

if (!READ_ONCE(vblank->enabled)) {
*vblank_time = ktime_get();
return true;
}

*vblank_time = READ_ONCE(output->vblank_hrtimer.node.expires);

if (WARN_ON(*vblank_time == vblank->time))
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