[PATCH v5 0/3] drm/vc4: Add a load tracker

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

Hi,

Here is a fourth iteration of the VC4 load tracking series, which was
initially developed by Boris Brezillon and that I have now taken over.

This new iteration takes in account comments from v3 and comes with a
new approach for avoiding underrun reports when reconfiguring the
pipeline. It is now based on detection instead of delaying the underrun
interrupt unmasking.

It can be tested with a dedicated IGT GPU Tools series:
  VC4 load tracker testing

Changes since v4:
* Unmasked underrun in vc4_crtc_handle_page_flip instead of the previous
  workaround for detecting out-of-sync display lists causing underruns;
* Added comments where it felt relevant;
* Made underrun masking/unmasking per-channel to avoid race conditions
  resulting in unwanted masking/unmasking;
* Added a check for unmasked interrupt before acting upon it;
* Disabled shortline/underrun interrupts at initial config time;
* Added collected Reviewed-by tags.

Changes since v3:
* Returned IRQ_NONE for short line interrupt to avoid storm;
* Made register definitions with per-channel offsets more direct;
* cleaned all IRQ fields instead of writing back the status bit as
  advised by docs;
* Reworked first commit's message;
* Removed in-commit changelogs with inconsistent revision numbers;
* Removed explicit wait for sync before unmasking underrun interrupt;
* Checked that the display lists are synced before reporting underrun;

Cheers,

Paul

Boris Brezillon (2):
  drm/vc4: Report HVS underrun errors
  drm/vc4: Add a load tracker to prevent HVS underflow errors

Paul Kocialkowski (1):
  drm/vc4: Add a debugfs entry to disable/enable the load tracker

 drivers/gpu/drm/vc4/vc4_crtc.c    |   8 ++
 drivers/gpu/drm/vc4/vc4_debugfs.c |  10 +++
 drivers/gpu/drm/vc4/vc4_drv.c     |   1 +
 drivers/gpu/drm/vc4/vc4_drv.h     |  24 ++++++
 drivers/gpu/drm/vc4/vc4_hvs.c     |  95 +++++++++++++++++++++++
 drivers/gpu/drm/vc4/vc4_kms.c     | 122 +++++++++++++++++++++++++++++-
 drivers/gpu/drm/vc4/vc4_plane.c   |  57 ++++++++++++++
 drivers/gpu/drm/vc4/vc4_regs.h    |  51 ++++---------
 8 files changed, 332 insertions(+), 36 deletions(-)

-- 
2.20.1