kernel_ [drm_drm_atomic_helper_wait_for_dependencies [drm_kms_helper]] _ERROR_ [CRTC_37_crtc-0] flip_done timed out - Red Hat Customer Portal.pdf

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kernel:

[drm:drm_atomic_helper_wait_for_depen

[drm_kms_helper]] *ERROR*…

Red Hat Enterprise Linux 7

Red Hat Enterprise Linux 8

RHEL guest running on VMware hypervisor

Framebuffer driver

The following error messages are logged in messages file while the server

is running.

RHEL 7:

Sep 11 05:23:24 hostname kernel: [drm:drm_atomic_helper_wait_for_dependencies

[drm_kms_helper]] *ERROR* [CRTC:37:crtc-0] flip_done timed out

Sep 11 05:23:34 hostname kernel: [drm:drm_atomic_helper_wait_for_dependencies

[drm_kms_helper]] *ERROR* [PLANE:33:plane-0] flip_done timed out

RHEL 8:

Nov 1 20:30:28 hostname kernel: [drm:drm_atomic_helper_wait_for_dependencies

[drm_kms_helper]] *ERROR* [CRTC:38:crtc-0] flip_done timed out

Nov 1 20:30:38 hostname kernel: [drm:drm_atomic_helper_wait_for_dependencies

[drm_kms_helper]] *ERROR* [PLANE:34:plane-0] flip_done timed out

What do I do to resolve these errors?

VMWare's engineering team has stated that this message is harmless on

their hypervisors.

For RHEL 7, this issue is tracked in Bug 1792515 .

For RHEL 8, this issue is tracked in Bug 1884401 .

The bugzilla tickets were closed by a representative from VMWare as "won't

fix" due to their inability to reproduce the issue in house

If you see this error, and also have a GUI performance issue, VMWare has

asked that you open a case with them for further analysis.

The following error messages are logged in messages file while the

server is running. RHEL 7: Sep 11 ......

“

环境

问题

决议

VMWare's engineering team has stated that this message is harmless.

The kernel code that prints this message prints a warning that a page flip in

the GPU hardware has not completed before the timeout period. In the

case of VMWare the GPU is virtualized.

/* Currently no support for overwriting flips, hence

* stall for previous one to execute completely. */

ret = wait_for_completion_timeout(&commit->flip_done,

messages (displayport code) (int)

What are GPU page flips?

Page flipping is a synchronization mechanism that replaces the frame buffer being scanned

out by the CRTC with a new frame buffer during vertical blanking, avoiding tearing (except

when requested otherwise through the DRM_MODE_PAGE_FLIP_ASYNC flag). When an application

requests a page flip the DRM core verifies that the new frame buffer is large enough to be

scanned out by the CRTC in the currently configured mode and then calls this hook with a

pointer to the new frame buffer.

The driver must wait for any pending rendering to the new framebuffer to complete before

executing the flip. It should also wait for any pending rendering from other drivers if the

underlying buffer is a shared dma-buf.

An application can request to be notified when the page flip has completed. The drm core

will supply a struct drm_event in the event parameter in this case. This can be handled by

the drm_crtc_send_vblank_event() function, which the driver should call on the provided

event upon completion of the flip. Note that if the driver supports vblank signalling and

timestamping the vblank counters and timestamps must agree with the ones returned from page

flip events. With the current vblank helper infrastructure this can be achieved by holding

a vblank reference while the page flip is pending, acquired through drm_crtc_vblank_get()

and released with drm_crtc_vblank_put(). Drivers are free to implement their own vblank

counter and timestamp tracking though, e.g. if they have accurate timestamp registers in

hardware.

https://docs.kernel.org/gpu/drm-kms.html?

highlight=page%20flipping%20synchronization%20mechanism

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