[v6,0/3] drm/vkms: Introduces writeback support

Message

Rodrigo Siqueira Aug. 30, 2020, 2:19 p.m. UTC

This is the V5 version of a series that introduces the writeback support
to VKMS. The first two patches of this series are a pre-work for the
latest patch that adds the writeback connector, this patchset can be seen
in two parts:

* A pre-work that aims to make vkms composer operations a little bit more
  generic; these patches try to centralize the vkms framebuffer operations.
* The final patch enables the support for writeback in vkms.

In the previous review, Emil suggested multiple changes in the series. I
tried to apply most of the recommendations except for some suggestions
which I was not able to incorporate due to compilation issues, or other
suggestions that may complicate this series review. I left some changes
for future patches for keeping this patchset simple with the hope of
landing this feature soon in order to support VKMS user's requirements.
Emil, let me know if you want me to change any other thing.

It is important to highlight that from the previous series to the
current version of this patchset we had some changes in the VKMS that
made it unstable.  In particular, our previous writeback series stopped
working properly due to changes in our commit tail.  Thanks to Melissa
working in the instability issue and her latest fixes to VKMS, I finally
could update writeback and make it work again. The main update in the
latest patch is the use of vkms_set_composer when the writeback work
starts (enable composer) and after the writeback end (disable composer).

V6:
- Rebase and tiny fixes

Best regards

Rodrigo Siqueira (3):
  drm/vkms: Decouple crc operations from composer
  drm/vkms: Compute CRC without change input data
  drm/vkms: Add support for writeback

 drivers/gpu/drm/vkms/Makefile         |   9 +-
 drivers/gpu/drm/vkms/vkms_composer.c  |  98 ++++++++++++------
 drivers/gpu/drm/vkms/vkms_drv.h       |  11 +-
 drivers/gpu/drm/vkms/vkms_output.c    |   4 +
 drivers/gpu/drm/vkms/vkms_writeback.c | 142 ++++++++++++++++++++++++++
 5 files changed, 228 insertions(+), 36 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/vkms_writeback.c