Hello, On Wed, May 18, 2022 at 08:30:06PM +0200, Thomas Zimmermann wrote: > Open Firmware provides basic display output via the 'display' node. > DT platform code already provides a device that represents the node's > framebuffer. Add a DRM driver for the device. The display mode and > color format is pre-initialized by the system's firmware. Runtime > modesetting via DRM is not possible. The display is useful during > early boot stages or as error fallback. > > Similar functionality is already provided by fbdev's offb driver, > which is insufficient for modern userspace. The old driver includes > support for BootX device tree, which can be found on old 32-bit > PowerPC Macintosh systems. If these are still in use, the > functionality can be added to ofdrm or implemented in a new > driver. As with simepldrm, the fbdev driver cannot be selected is > ofdrm is already enabled. > > Two noteable points about the driver: > > * Reading the framebuffer aperture from the device tree is not > reliable on all systems. Ofdrm takes the heuristics and a comment > from offb to pick the correct range. > > * No resource management may be tied to the underlying PCI device. > Otherwise the handover to the native driver will fail with a resource > conflict. PCI management is therefore done as part of the platform > device's cleanup. > > The driver has been tested on qemu's ppc64le emulation. The device > hand-over has been tested with bochs. > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > --- > MAINTAINERS | 1 + > drivers/gpu/drm/tiny/Kconfig | 12 + > drivers/gpu/drm/tiny/Makefile | 1 + > drivers/gpu/drm/tiny/ofdrm.c | 748 ++++++++++++++++++++++++++++++++++ > drivers/video/fbdev/Kconfig | 1 + > 5 files changed, 763 insertions(+) > create mode 100644 drivers/gpu/drm/tiny/ofdrm.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 43d833273ae9..090cbe1aa5e3 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -6395,6 +6395,7 @@ L: dri-devel@xxxxxxxxxxxxxxxxxxxxx > S: Maintained > T: git git://anongit.freedesktop.org/drm/drm-misc > F: drivers/gpu/drm/drm_aperture.c > +F: drivers/gpu/drm/tiny/ofdrm.c > F: drivers/gpu/drm/tiny/simpledrm.c > F: include/drm/drm_aperture.h > > diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig > index 627d637a1e7e..0bc54af42e7f 100644 > --- a/drivers/gpu/drm/tiny/Kconfig > +++ b/drivers/gpu/drm/tiny/Kconfig > @@ -51,6 +51,18 @@ config DRM_GM12U320 > This is a KMS driver for projectors which use the GM12U320 chipset > for video transfer over USB2/3, such as the Acer C120 mini projector. > > +config DRM_OFDRM > + tristate "Open Firmware display driver" > + depends on DRM && MMU && PPC Does this build with !PCI? The driver uses some PCI functions, so it might possibly break with randconfig. I don't think there are practical !PCI PPC configurations. Thanks Michal
