[v5,0/5] drm: Add driver for PowerPC OF displays

Message

Thomas Zimmermann Oct. 11, 2022, 3:07 p.m. UTC

PowerPC's Open Firmware offers a simple display buffer for graphics
output. Add ofdrm, a DRM driver for the device. As with the existing
simpledrm driver, the graphics hardware is pre-initialized by the
firmware. The driver only provides blitting, no actual DRM modesetting
is possible.

Patch 1 adds ofdrm, which has again been significantly reworked.
The FWFB library has been removed infavor of various functions in
existing DRM helper libraries. Ofdrm now supports damage iterators
and synchronization for imported GEM BOs.

Patches 2 to 4 add support for color management. The code has been
taken from fbdev's offb. I have no hardware available for testing the
functionality. Qemu's stdvga apparently does not support gamma tables
in RGB modes. I verified that the color management code is executed
by running Gnome's night-mode settings, but the display's color tone
does not change.

Patch 5, which is new in version 4 of this patchset, adds support for
big-endian scanout buffers. It works at least with qemu's ppc64
emulation. Fbdev emulation and pixman rendering works. GL rendering
produces incorrect colors.

Tested by running fbdev emulation, Wayland Gnome, and Weston on qemu's
ppc64le and ppc64 emulation. 

Thomas Zimmermann (5):
  drm/ofdrm: Add ofdrm for Open Firmware framebuffers
  drm/ofdrm: Add CRTC state
  drm/ofdrm: Add per-model device function
  drm/ofdrm: Support color management
  drm/ofdrm: Support big-endian scanout buffers

 MAINTAINERS                         |    1 +
 drivers/gpu/drm/drm_format_helper.c |   10 +
 drivers/gpu/drm/tiny/Kconfig        |   13 +
 drivers/gpu/drm/tiny/Makefile       |    1 +
 drivers/gpu/drm/tiny/ofdrm.c        | 1424 +++++++++++++++++++++++++++
 drivers/video/fbdev/Kconfig         |    1 +
 6 files changed, 1450 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/ofdrm.c