Adds support for ConfigFS to VKMS!

Intro
=====

At long last, we're back!

This patchset adds basic ConfigFS support to VKMS, allowing users to
build new DRM devices with user-defined DRM objects and object
relationships by creating, writing, and symlinking files.

Usage
=====

After installing these patches, you can create a VKMS device with two
displays and a movable overlay like so (this is documented in the
patches):

  $ modprobe vkms enable_overlay=1 enable_cursor=1 enable_writeback=1
  $ mkdir -p /config/
  $ mount -t configfs none /config

  $ export DRM_PLANE_TYPE_PRIMARY=1
  $ export DRM_PLANE_TYPE_CURSOR=2
  $ export DRM_PLANE_TYPE_OVERLAY=0

  $ mkdir /config/vkms/test

  $ mkdir /config/vkms/test/planes/primary
  $ echo $DRM_PLANE_TYPE_PRIMARY > /config/vkms/test/planes/primary/type

  $ mkdir /config/vkms/test/planes/other_primary
  $ echo $DRM_PLANE_TYPE_PRIMARY > /config/vkms/test/planes/other_primary/type

  $ mkdir /config/vkms/test/planes/cursor
  $ echo $DRM_PLANE_TYPE_CURSOR > /config/vkms/test/planes/cursor/type

  $ mkdir /config/vkms/test/planes/overlay
  $ echo $DRM_PLANE_TYPE_OVERLAY > /config/vkms/test/planes/overlay/type

  $ mkdir /config/vkms/test/crtcs/crtc
  $ mkdir /config/vkms/test/crtcs/crtc_other
  $ mkdir /config/vkms/test/encoders/encoder
  $ mkdir /config/vkms/test/connectors/connector

  $ ln -s /config/vkms/test/encoders/encoder /config/vkms/test/connectors/connector/possible_encoders
  $ ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/encoders/encoder/possible_crtcs/
  $ ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/primary/possible_crtcs/
  $ ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/cursor/possible_crtcs/
  $ ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/overlay/possible_crtcs/
  $ ln -s /config/vkms/test/crtcs/crtc_other /config/vkms/test/planes/overlay/possible_crtcs/
  $ ln -s /config/vkms/test/crtcs/crtc_other /config/vkms/test/planes/other_primary/possible_crtcs/

  $ echo 1 > /config/vkms/test/enabled

Changes within core VKMS
========================

This introduces a few important changes to the overall structure of
VKMS:

  - Devices are now memory managed!
  - Support for multiple CRTCs and other objects has been added

Since v1
========

  - Added DRMM memory management to automatically clean up resources
  - Added a param to disable the default device
  - Renamed "cards" to "devices" to improve legibility
  - Added a lock for the configfs setup handler
  - Moved all the new docs into the relevant .c file
  - Addressed as many of sean@poorly.run as possible

Testing
=======

  - New IGT tests (see
    gitlab.freedesktop.org/jshargo/igt-gpu-tools/-/merge_requests/1)
  - Existing IGT tests (excluding .*suspend.*, including .*kms_flip.*
    .*kms_writeback.* .*kms_cursor_crc.*, .*kms_plane.*)

Outro
=====

I'm excited to share these changes, it's my still my first kernel patch
and I've been putting a lot of love into these.

Jim Shargo (6):
  drm/vkms: Back VKMS with DRM memory management instead of static
    objects
  drm/vkms: Support multiple DRM objects (crtcs, etc.) per VKMS device
  drm/vkms: Provide platform data when creating VKMS devices
  drm/vkms: Add ConfigFS scaffolding to VKMS
  drm/vkms: Support enabling ConfigFS devices
  drm/vkms: Add a module param to enable/disable the default device

 Documentation/gpu/vkms.rst            |  17 +-
 drivers/gpu/drm/Kconfig               |   1 +
 drivers/gpu/drm/vkms/Makefile         |   1 +
 drivers/gpu/drm/vkms/vkms_composer.c  |  28 +-
 drivers/gpu/drm/vkms/vkms_configfs.c  | 657 ++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_crtc.c      |  97 ++--
 drivers/gpu/drm/vkms/vkms_drv.c       | 208 +++++---
 drivers/gpu/drm/vkms/vkms_drv.h       | 166 +++++--
 drivers/gpu/drm/vkms/vkms_output.c    | 299 ++++++++++--
 drivers/gpu/drm/vkms/vkms_plane.c     |  44 +-
 drivers/gpu/drm/vkms/vkms_writeback.c |  26 +-
 11 files changed, 1312 insertions(+), 232 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/vkms_configfs.c

-- 
2.41.0.162.gfafddb0af9-goog