The RCAR-DU utilises a running VSPD pipeline to perform processing for the display pipeline. This presents the opportunity for some race conditions to affect the quality of the display output.
To prevent reporting page flips early, we must track this timing through the VSP1, and only allow the rcar-du object to report the page-flip completion event after the VSP1 has processed.
This series ensures that tearing and flicker is prevented, without introducing the performance impact mentioned in the previous series.
[PATCH 1/3] handles potential race conditions in vsp1_dlm_irq_frame_end() and prevents signalling the frame end in this event. [PATCH 2/3] extends the VSP1 to allow a callback to be registered giving the VSP1 the ability to notify completion events. [PATCH 3/3] utilises the callback extension to send page flips at the end of VSP processing for Gen3 platforms.
These patches have been tested by introducing artificial delays in the commit code paths and verifying that no visual tearing or flickering occurs.
Extensive testing around the race window has been performed by dynamically adapting the artificial delay between 10, and 17 seconds in 100uS increments for periods of 5 seconds on each delay test. These tests have successfully run for 3 hours.
Manual start/stop testing has also been performed.
Kieran Bingham (3): v4l: vsp1: Postpone frame end handling in event of display list race v4l: vsp1: Extend VSP1 module API to allow DRM callbacks drm: rcar-du: Register a completion callback with VSP1
drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 8 ++++++-- drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 1 + drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 9 +++++++++ drivers/media/platform/vsp1/vsp1_dl.c | 19 +++++++++++++++++-- drivers/media/platform/vsp1/vsp1_dl.h | 2 +- drivers/media/platform/vsp1/vsp1_drm.c | 17 +++++++++++++++++ drivers/media/platform/vsp1/vsp1_drm.h | 11 +++++++++++ drivers/media/platform/vsp1/vsp1_pipe.c | 13 ++++++++++++- include/media/vsp1.h | 13 +++++++++++++ 9 files changed, 87 insertions(+), 6 deletions(-)
base-commit: cdb5795cbc4ddbe5082c25c52ebc1d811ac3849e